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How can i change the background cell color after the user edited some text

Going from the previous question i had asked that related to color text change after edit. Now it has been requested that i should not highlight the edited text but change the background color.
This is what i want now.
Load existing file with the data to the DataGridView
After loading, DataGridView will populate data
The user will edit text from any cell
After editing the text,
Background color of the edited cell will change color to red,
Only for the edited cell,
How can i change the background color of the edited cell in the DataGridView ?
This is what i tried by changing the background color of the cell.
private void Gridview_Output_CellBeginEdit_1(object sender, DataGridViewCellCancelEventArgs e)
{
DataGridViewCell cell = Gridview_Output[e.ColumnIndex, e.RowIndex];
cell.Tag = cell.Value != null ? cell.Value : "";
if (cell.OwningColumn.Name == "ValueOut")
cell.Style.BackColor = Color.Yellow;
}
global
List<DataGridViewCell> dgvc_List = new List<DataGridViewCell>();
Save button
private void btnSave_Click(object sender, EventArgs e)
{
dgvc_List.Add(cell);
foreach (DataGridViewCell d in dgvc_List)
{
d.Style.BackColor = Color.White;
}
dgvc_List.Clear();
}

You might want to use the TextChanged event ( https://msdn.microsoft.com/en-us/library/system.windows.forms.control.textchanged(v=vs.110).aspx ) to detect whenever the user is changing the content of the TextBox (you might want to apply some logic here to avoid to trigger it when loading the data in the control). When the even triggers, you can then change the Background color of the control ( https://msdn.microsoft.com/en-us/library/s2kh9x59(v=vs.110).aspx )

Add a new event on CellEndEdit instead:
private void Gridview_Output_CellEndEdit_1(object sender, DataGridViewCellCancelEventArgs e)
{
DataGridViewCell cell = Gridview_Output[e.ColumnIndex, e.RowIndex];
cell.Tag = cell.Value != null ? cell.Value : "";
if (cell.OwningColumn.Name == "ValueOut")
cell.Style.BackColor = Color.Yellow;
}
This is because you invoke the event before the editing is done, instead what you really want is show a different color when the job is done.

Just to further what Donbabbeo has answered...
I take it you only want to change the background ONLY IF the cell value has actually been changed. Using Donbabbeo's answer will change the BackColor regardless every time editing occurs irrespective of whether the value has changed or not.
I suggest you use both the CellBeginEdit and CellEndEdit events together.
To begin with you need to 'remember' the original value of the cell being edited.
string originalValue; // Define a global outside
private void Gridview_Output_CellBeginEdit_1(object sender, DataGridViewCellCancelEventArgs e)
{
originalValue = Gridview_Output[e.ColumnIndex, e.RowIndex].Value.ToString();
}
And then when you complete the edit you check back against the originalValue, only changing the background color if changes had actually been made
private void Gridview_Output_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
DataGridViewCell cell = Gridview_Output[e.ColumnIndex, e.RowIndex];
if (cell.Value.ToString() != originalValue)
{
cell.Style.BackColor = Color.Red;
}
}
If you still want to check that the OwningColumn.Name is a specific value or any other checks for that matter then add a further if statement after you check against the original value.
UPDATE
Changing the cell colors back to their original should be done exactly as Donbabbeo has described in his comment UNLESS you are dealing with a very large DataGridView and then it would be much more efficient to create a generic list of cells to be added to when the change complets & then when saved iterate only through the List<> to revert.
It would be implemented something like this.
First of all the list would need to be declared outside
List<DataGridViewCell> dgvc_List = new List<DataGridViewCell>();
Once the list is declared you would then add specific cells once you were sure that the value was different to the original and that the the BackColor had been changed.
In saying that the following would then be added directly after the color change in the CellEndEdit event.
dgvc_List.Add(cell);
The list will then continue to grow with every confirmed edit until you were ready to do something with it upon the save method, or whatever other method you wanted really, where you would call the following
foreach (DataGridViewCell d in dgvc_List)
{
d.Style.BackColor = Color.White; // Or Any Color
}
dgvc_List.Clear(); // Clears the list ready to go again
Its a little more to code but much more efficient in the long run.

Why didn't trigger the CellEndEdit event of DataGridView

All,I knew we can set a column editable for a DataGridView.
And when finish editing the cell. the CellEndEdit event would be triggered.
But I just want to know why didn't end the edit of cell when I click the blank area of DataGridView. And click the area out of DataGridView doesn't trigger it too. only clicking the other cells could make it happen. It really doesn't make sense. Could anyone know why ? and How to make it ? It try to use the Click event of the DataGridView, But When I click the cell, It also trigger the DataGridView_click event.
private void dgvList_Click(object sender, EventArgs e)
{
dgvFileList.EndEdit();
}

Try using the HitTest function in the MouseDown event of the grid:
void dgvFileList_MouseDown(object sender, MouseEventArgs e) {
DataGridView.HitTestInfo hit = dgvFileList.HitTest(e.X, e.Y);
if (hit.RowIndex < 0 | hit.ColumnIndex < 0) {
dgvFileList.EndEdit();
}
}
Clicking outside the DataGridView control would require hitting a focusable control.

Before BeginEdit. Set a variable to identify if current state is edit mode.
bBeginEdit = true;
dgvFileList.BeginEdit(false);
In the Form_Click event
if (bBeginEdit)
{
dgvFileList.EndEdit();
bBeginEdit = false;
}
Thanks,
Joe

CellEndEdit() causes the event to be fired only if the cell was in edit mode (see Joe.wang's response). You can simply preceed CellEndEdit() with CellBeginEdit() to enter Edit mode (code from CellContentClick-handler, PickNewFont() is a wrapper for the FontDialog):
[...]
else if (String.Compare(rowName, "Font name") == 0) // user clicks on Font-row
{
dgvConfigSettings.BeginEdit(true);
Font newFont = PickNewFont(fontName, fontSize, fontStyle);
dgvConfigSettings.CurrentCell.Tag = newFont; // a bit dirty.... but that way we can pick-up the font in the panel-handler more easily
dgvConfigSettings.CurrentCell.Value = newFont.Name.ToString();
dgvConfigSettings.EndEdit();
}

How to activate combobox on first click (Datagridview)

In winforms, you need to click the combobox twice to properly activate it - the first time to focus it, the second time to actually get the dropdown list.
How do I change this behavior so that it activates on the very first click?
This is for DATAGRIDVIEW combobox.

I realize this is an old question, but I figured I would give my solution to anyone out there that may need to be able to do this.
While I couldn't find any answers to do exactly this... I did find an answer to a different question that helped me.
This is my solution:
private void datagridview_CellEnter(object sender, DataGridViewCellEventArgs e)
{
bool validClick = (e.RowIndex != -1 && e.ColumnIndex != -1); //Make sure the clicked row/column is valid.
var datagridview = sender as DataGridView;
// Check to make sure the cell clicked is the cell containing the combobox
if(datagridview.Columns[e.ColumnIndex] is DataGridViewComboBoxColumn && validClick)
{
datagridview.BeginEdit(true);
((ComboBox)datagridview.EditingControl).DroppedDown = true;
}
}
private void datagridview_CurrentCellDirtyStateChanged(object sender, EventArgs e)
{
datagridview.CommitEdit(DataGridViewDataErrorContexts.Commit);
}
The above code must be tied into the CellEnter event of the datagridview.
I hope this helps!
edit: Added a column index check to prevent crashing when the entire row is selected.
Thanks, Up All Night for the above edit
edit2: Code is now to be tied to the CellEnter rather than the CellClick event.
Thanks, HaraldDutch for the above edit
edit3: Any changes will committed immediately, this will save you from clicking in another cell in order to update the current combobox cell.

Set the following on your DataGridView:
EditMode = EditOnEnter
This is probably the easiest solution and has been the workaround for many users here on SO when this question gets asked.
EDIT :
Per here do the following:
Set the Editmode:
EditMode = EditOnKeystrokeOrF2
Modify the EditingControlShowing event on the datagridview:
private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
ComboBox ctl = e.Control as ComboBox;
ctl.Enter -= new EventHandler(ctl_Enter);
ctl.Enter += new EventHandler(ctl_Enter);
}
void ctl_Enter(object sender, EventArgs e)
{
(sender as ComboBox).DroppedDown = true;
}
This will get you your desired results. Let me know if that doesn't do it.

I changed only the EditMode property of the datagridview to EditOnEnter and it's working perfectly.
EditMode = EditOnEnter

If you set the entire grid to EditOnEnter, you can get some pretty funky activity when you are on a text column. Here's my solution, which should be self explanatory. If you did not know the column names, you could just check the cell type on mousemove.
Private Sub GridView_CellMouseMove(sender As Object, e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles GridView.CellMouseMove
Select Case GridView.Columns(e.ColumnIndex).Name
Case "Ad_Edit", "Size_Caption", "Demo_Code"
GridView.EditMode = DataGridViewEditMode.EditOnEnter
Case Else
GridView.EditMode = DataGridViewEditMode.EditOnKeystrokeOrF2
End Select
End Sub

Set the DropDownStyle property of your combo box to DropDownList...

Perhaps old.. But make sure to set ReadOnly property to false, else the cell wont enter editmode and therefore the EditingControl returns null and casting DroppedDown = true will cast a NullReferencException.

How to change listview selected row backcolor even when focus on another control?

I have a program which uses a barcode scanner as input device so that means I need to keep the focus on a text box.
The program has a listview control and I select one of the items programatically when a certain barcode is scanned. I set the background color of the row by:
listviewitem.BackColor = Color.LightSteelBlue;
Things I have tried:
listview.HideSelection set to false
call listview.Focus() after setting the color
listviewitem.Focused set to true
call listview.Invalidate
call listview.Update()
call listview.Refresh()
different combinations of the above
I've also did combinations above stuff in a timer so that they are called on a different thread but still no success.
Any ideas?
More info:
The key here is the control focus. The listview control does not have the focus when I select one of the items.
I select one item by doing:
listView1.Items[index].Selected = true;
the Focus is always in the textbox.
the computer does not have keyboard or mouse, only a barcode reader.
I have this code to keep the focus on the textbox:
private void txtBarcode_Leave(object sender, EventArgs e)
{
this.txtBarcode.Focus();
}
You need to have a textbox add that code to simulate my problem.

What you describe works exactly as expected, assuming that you've set the HideSelection property of the ListView control to False. Here's a screenshot for demonstration purposes. I created a blank project, added a ListView control and a TextBox control to a form, added some sample items to the ListView, set its view to "Details" (although this works in any view), and set HideSelection to false. I handled the TextBox.Leave event just as you showed in the question, and added some simple logic to select the corresponding ListViewItem whenever its name was entered into the TextBox. Notice that "Test Item Six" is selected in the ListView:
Now, as I suspected initially, you're going to mess things up if you go monkeying around with setting the BackColor property yourself. I'm not sure why you would ever want to do this, as the control already uses the default selection colors to indicate selected items by default. If you want to use different colors, you should change your Windows theme, rather than trying to write code to do it.
In fact, if I add the line item.BackColor = Color.LightSteelBlue in addition to my existing code to select the ListViewItem corresponding to the name typed into the TextBox, I get exactly the same thing as shown above. The background color of the item doesn't change until you set focus to the control. That's the expected behavior, as selected items look different when they have the focus than they do when their parent control is unfocused. Selected items on focused controls are painted with the system highlight color; selected items on unfocused controls are painted with the system 3D color. Otherwise, it would be impossible to tell whether or not the ListView control had the focus. Moreover, any custom BackColor property is completely ignored by the operating system when the ListView control has the focus. The background gets painted in the default system highlight color.
Explicitly setting the focus to the ListView control, of course, causes the custom background color to be applied to the ListViewItem, and things render with a color that very much contrasts with the color scheme that I've selected on my computer (remember, not everyone uses the defaults). The problem, though, becomes immediately obvious: you can't set the focus to the ListView control because of the code you've written in the TextBox.Leave event handler method!
I can tell you right now that setting the focus in a focus-changing event is the wrong thing to do. It's a hard rule in Windows you're not allowed to do things like that, and the documentation even warns you explicitly not to do it. Presumably, your answer will be something along the lines of "I have to", but that's no excuse. If everything were working as expected, you wouldn't be asking this question in the first place.
So, what now? Your application's design is broken. I suggest fixing it. Don't try and monkey with setting the BackColor property yourself to indicate that an item is selected. It conflicts with the default way that Windows highlights selected items. Also, don't try and set the focus in a focus-changing event. Windows explicitly forbids this, and the documentation is clear that you're not supposed to do this. If the target computer doesn't have a mouse or keyboard, it's unclear how the user is going to set focus to anything else in the first place, unless you write code to do it, which you shouldn't be doing.
But I have surprisingly little faith that you'll want to fix your application. People who ignore warnings in the documentation tend to be the same people who don't listen to well-meaning advice on Q&A sites. So I'll throw you a bone and tell you how to get the effect you desire anyway. The key lies in not setting the ListViewItem's Selected property, which avoids the conflict between your custom BackColor and the system default highlight color. It also frees you from having to explicitly set the focus to the ListView control and back again (which, as we established above, isn't actually happening, given your Leave event handler method). Doing that produces the following result:
And here's the code—it's not very pretty, but this is just a proof of concept, not a sample of best practice:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
listView1.View = View.Details;
listView1.HideSelection = false;
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
foreach (ListViewItem item in listView1.Items)
{
if (item.Text == textBox1.Text)
{
item.BackColor = Color.LightSteelBlue;
return;
}
}
}
private void textBox1_Leave(object sender, EventArgs e)
{
this.textBox1.Focus();
}
}

A standard ListView does not let you set the background color of a selected row. The background (and foreground) colors of a selected row are always controlled by the theme of the OS.
You have to owner draw your ListView to get around this OR you can use ObjectListView. ObjectListView is an open source wrapper around .NET WinForms ListView, which makes it much easier to use, as well as easily allowing things that are very difficult in a normal ListView -- like changed the colors of selected rows.
this.objectListView1.UseCustomSelectionColors = true;
this.objectListView1.HighlightBackgroundColor = Color.Lime;
this.objectListView1.UnfocusedHighlightBackgroundColor = Color.Lime;
This shows the ObjectListView when it does not have focus.

Here's a solution for a ListView that does not allow multiple selections and
does not have images (e.g. checkboxes).
Set event handlers for the ListView (in this example it's named listView1):
DrawItem
Leave (invoked when the ListView's focus is lost)
Declare a global int variable (i.e. a member of the Form that contains the ListView,
in this example it's named gListView1LostFocusItem) and assign it the value -1
int gListView1LostFocusItem = -1;
Implement the event handlers as follows:
private void listView1_Leave(object sender, EventArgs e)
{
// Set the global int variable (gListView1LostFocusItem) to
// the index of the selected item that just lost focus
gListView1LostFocusItem = listView1.FocusedItem.Index;
}
private void listView1_DrawItem(object sender, DrawListViewItemEventArgs e)
{
// If this item is the selected item
if (e.Item.Selected)
{
// If the selected item just lost the focus
if (gListView1LostFocusItem == e.Item.Index)
{
// Set the colors to whatever you want (I would suggest
// something less intense than the colors used for the
// selected item when it has focus)
e.Item.ForeColor = Color.Black;
e.Item.BackColor = Color.LightBlue;
// Indicate that this action does not need to be performed
// again (until the next time the selected item loses focus)
gListView1LostFocusItem = -1;
}
else if (listView1.Focused) // If the selected item has focus
{
// Set the colors to the normal colors for a selected item
e.Item.ForeColor = SystemColors.HighlightText;
e.Item.BackColor = SystemColors.Highlight;
}
}
else
{
// Set the normal colors for items that are not selected
e.Item.ForeColor = listView1.ForeColor;
e.Item.BackColor = listView1.BackColor;
}
e.DrawBackground();
e.DrawText();
}
Note: This solution will result in some flicker. A fix for this involves subclassing the ListView control so you
can change the protected property DoubleBuffered to true.
public class ListViewEx : ListView
{
public ListViewEx() : base()
{
this.DoubleBuffered = true;
}
}

On SelectedIndexChanged:
private void lBxDostepneOpcje_SelectedIndexChanged(object sender, EventArgs e)
{
ListViewItem item = lBxDostepneOpcje.FocusedItem as ListViewItem;
ListView.SelectedIndexCollection lista = lBxDostepneOpcje.SelectedIndices;
foreach (Int32 i in lista)
{
lBxDostepneOpcje.Items[i].BackColor = Color.White;
}
if (item != null)
{
item.Selected = false;
if (item.Index == 0)
{
}
else
{
lBxDostepneOpcje.Items[item.Index-1].BackColor = Color.White;
}
if (lBxDostepneOpcje.Items[item.Index].Focused == true)
{
lBxDostepneOpcje.Items[item.Index].BackColor = Color.LightGreen;
if (item.Index < lBxDostepneOpcje.Items.Count-1)
{
lBxDostepneOpcje.Items[item.Index + 1].BackColor = Color.White;
}
}
else if (lBxDostepneOpcje.Items[item.Index].Focused == false)
{
lBxDostepneOpcje.Items[item.Index].BackColor = Color.Blue;
}
}
}

You cant set focus on listview control in this situation. txtBarcode_Leave method will prevent this. But if you are desire to be able select listview items by clicking on them, just add code below to MouseClick event handler of listview:
private void listView1_MouseClick(object sender, MouseEventArgs e)
{
ListView list = sender as ListView;
for (int i = 0; i < list.Items.Count; i++)
{
if (list.Items[i].Bounds.Contains(e.Location) == true)
{
list.Items[i].BackColor = Color.Blue; // highlighted item
}
else
{
list.Items[i].BackColor = SystemColors.Window; // normal item
}
}
}

This change color of selected item. but only in state listview not have focus.
Make sure HideSelection is !TRUE! and simple use this code:
private void ListView_SelectedIndexChanged(object sender, EventArgs e){
foreach(ListViewItem it in ListView.Items)
{
if (it.Selected && it.BackColor != SystemColors.Highlight)
{
it.BackColor = SystemColors.Highlight;
it.ForeColor = SystemColors.HighlightText;
}
if (!it.Selected && it.BackColor != SystemColors.Window)
{
it.BackColor = SystemColors.Window;
it.ForeColor = SystemColors.WindowText;
}
}
}

Just do like this:
Set property UnfocusedHighlighForegroundColor = "Blue"
Set property UnfocusedHighlighBackgroundColor = "White"
Set property UserCustomSelectionColors = true
Good luck :)

DataGridView throwing "InvalidOperationException: Operation is not valid..." when adding a row

I want an OpenFileDialog to come up when a user clicks on a cell, then display the result in the cell.
It all works, except that the DataGridView displays an extra row, for adding values to the list it's bound to. The row shows up if dataGridView.AllowUserToAddNewRows == true, which is what I want. What I don't want is for the application to crash when that row is edited programatically; instead, it should do exactly what it would do if the user had edited that row manually (add the new row to the underlying list, push another empty row onto the grid for adding values).
I read about SendKeys.Send(), which should make the DataGridView behave exactly as though the user had typed the value in; however, it does not work either. Here is what I am trying:
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
dataGridView1.CurrentCell = cell;
//simply doing a cell.Value = etc. will cause the program to crash
cell.ReadOnly = false;
dataGridView1.Columns[cell.ColumnIndex].ReadOnly = false;
dataGridView1.EditMode = DataGridViewEditMode.EditOnEnter;
dataGridView1.BeginEdit(true);
SendKeys.Send(openFileDialog1.FileName + "{Enter}");
dataGridView1.EndEdit();
cell.ReadOnly = true;
dataGridView1.Columns[cell.ColumnIndex].ReadOnly = true;
}
//I would expect the FileName would be in the cell now, and a new empty
//row tacked onto the end of the DataGridView, but it's not; the DataGridView
//is not changed at all.

I found a workaround on this page, though I don't know why it works
public MyForm()
{
InitializeComponent();
//Create a BindingSource, set its DataSource to my list,
//set the DataGrid's DataSource to the BindindingSource...
_bindingSource.AddingNew += OnAddingNewToBindingSource;
}
private void OnAddingNewToBindingSource(object sender, AddingNewEventArgs e)
{
if(dataGridView1.Rows.Count == _bindingSource.Count)
{
_bindingSource.RemoveAt(_bindingSource.Count - 1);
}
}
I'm getting very sick of spending so much time dealing with Visual Studio bugs...

I was having the same problem when trying to programattically edit cells with a binding source.
""Operation is not valid due to the current state of the object"
Which operation? What State? So helpful.
My code seem to work fine except when editing the last row in the grid.
Turns out the key is DataGridView.NotifiyCurrentCelldirty(true)
The correct sequence for programatically editing a cell, so it works the same as if the user did it.
(A new empty row appears when changing a cell in the last row) is something like this:
1) Make the cell to edit the current cell (do what ever you need to the current currentcell, first
like calling endEdit if it is in edit mode.)
2) Call DataGridview.BeginEdit(false)
3) Call DataGridView.NotifyCurrentCellDirty(true)
4) Modify the value.
5) Call DataGridView.EndEdit()
And you'll want to do something for the RowValidating and RowValidated events.
One of my routines for updating a cell value looks like this:
This is from a method in my class derived from DataGridView.
You could do the same thing from the containing form, calling
through a DataGridView instance, because the methods are public.
Here the calls are using an impliciit 'this.'
private void EnterTime()
{
if (CurrentRow == null) return;
SaveCurrentCell(); // Calls EndEdit() if CurrentCell.IsInEditMode
DataGridViewCell previous = CurrentCell;
CurrentCell = CurrentRow.Cells[CatchForm.TimeColumn];
BeginEdit(false);
NotifyCurrentCellDirty(true);
CurrentCell.Value = DateTime.Now;
EndEdit();
CurrentCell = previous;
}
I’m not sure why a separate call is needed.
Why doesn’t BeginEdit, or actually modifying the cell value, cause the right
things to happen?
And if you move the NotifyCurrentCellDirty call to after you actually modify the cell,
it doesn’t behave correctly either. All very annoying.

This is old, but I am running VS2010 and just come across this issue. I have a DataGridView bound to a List<T> using a BindingList<T>. I have a drag n' drop event on my DataGridView and it would throw this exception after deleting all rows from the DGV (except for the last blank one which one cannot delete) and then adding new rows to the DGV in the DragDrop handler via the BindingList<T>. This exception was not thrown if I simply added rows manually editing individual cells.
One solution I read said to handle the BindingList<T>.AddNew event, but I found that this event did not fire when calling BindingList<T>.Add() within the DragDrop event handler (I'm not sure why). I solved the issue by adding
if(bindingList.Count == 0)
bindingList.RemoveAt(0)
inside of the DragDrop event handler before adding new objects to bindingList. It seemed that adding an object to the bindingList failed when the only "object" in the bindingList was the one associated to the final blank row. The point of a BindingList<T> is to allow the developer to work with it instead of the DGV directly, but it seems doing so can cause problems in border cases.
The relationship between DGV rows and BindingList<T> rows seems to be a bit of a gray area. I have not spent much time investigating this, but it is not clear to me what is the state of the "object" in the BindingList<T> associated to the final (empty) row of the DGV. However, it does seem like the "object" at the end is only instantiated "correctly" when you interact with the final row directly (not via a DataSource).

Try this:
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
int row = e.RowIndex;
int clmn = e.ColumnIndex;
if(e.RowIndex == dataGridView1.Rows.Count- 1)
dataGridView1.Rows.Add();
dataGridView1.Rows[row].Cells[clmn].Value = openFileDialog1.FileName;
}
EDIT
I didn't notice that you are binding your datagridview :(
Ok, to solve it: use binding source, set its DataSource property to your list, then set the data source of the data grid view to this binding source. Now, the code should look like so:
public partial class frmTestDataGridView : Form
{
BindingSource bindingSource1 = new BindingSource();
List<string> datasource = new List<string>();
public frmTestDataGridView()
{
InitializeComponent();
datasource.Add("item1");
datasource.Add("item2");
datasource.Add("item3");
bindingSource1.DataSource = datasource;
dataGridView1.DataSource = bindingSource1;
}
private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
int row = e.RowIndex;
int clmn = e.ColumnIndex;
if (e.RowIndex == dataGridView1.Rows.Count - 1)
{
bindingSource1.Add("");
}
dataGridView1.Rows[row].Cells[clmn].Value = openFileDialog1.FileName;
}
}
}

Remember to use Row.BeginEdit() and Row.EndEdit() if you get this error while editing a value in a row, using DataGrid or GridEX from Janus (in my case). The sample code that Darrel Lee posted here (https://stackoverflow.com/a/9143590/1278771) remind me to use these instructions that I forgot to use and this solved the problem for me.