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Get the Vertex(Node) Object user clicked on in MSAGL

So, what is the way to retrieve the object that was under the mouse pointer when user clicked? I assume the gViewer must have some event to do that. In the tutorial i found this idea:
gViewer.SelectionChanged +=
new EventHandler(gViewer_SelectionChanged);
with gViewer_SelectionChanged being an event handler defined like this:
void gViewer_SelectionChanged(object sender, EventArgs e)
Although i added using statments for all 3 MSAGL dll's, i can't find the
Selection changedevent. Is there a special event for that, or am i looking the wrong way? Can it be that i need to handle some mouse event and get object based on it?
Sadly, there are only few MSAGL samples, no documentation and limited comments, so the more questions abount it here - the better.

do you mean get the infomation of each object?
viewer.Click += GraphNode_Click;
...
private void GraphNode_Click(object sender, EventArgs e)
{
GViewer viewer = sender as GViewer;
if (viewer.SelectedObject is Node)
{
Node node = viewer.SelectedObject as Node;
//...do works here
}
}

The code can not work:
viewer.Click += GraphNode_Click;
It should be like:
viewer.Click += EventHandler(Group_Click);

Different objects calling same method, how can I set the "caller's" property?

I have 15 images on my WPF application. I want it so that whenever MouseUp on any of the images is called.. it'll call the same method.
I would like to do something similar to the psuedo code written here.. This would save so much time instead of writing 15 individual methods for each button. How can I do something like this?
private void BluePick1_Image_MouseUp_1(object sender, MouseButtonEventArgs e)
{
sender.ImageSource = something;
}
thank you for any help

if your event is always on a button :
private void ButtonMouseUp(object sender, MouseButtonEventArgs e) {
((Button)sender).ImageSource = something;
}
and
button1.MouseUp += ButtonMouseUp;
button2.MouseUp += ButtonMouseUp;

How do I make buttons do the same thing?

I just started programming, and I want to use WinForms to make multiple buttons that you can click on to change from white to lime-green and back to white. I have done this for one button:
private void button1_Click(object sender, EventArgs e)
{
if (button1.BackColor != Color.Lime)
{
button1.BackColor = Color.Lime;
}
else
{
button1.BackColor = Color.White;
}
}
Now I could copy and paste that for all of the buttons, but I know that is inefficient; and if I use winforms to reference button1 on button2, it will just change the color of button1 (obviously).
So, do I need to use a helper method, new class, or something else? What would that look like?

There are a couple of approaches. One might be to create a common function which the different buttons call:
private void button1_Click(object sender, EventArgs e)
{
ChangeColor(button1);
}
private void ChangeColor(Button button)
{
if (button.BackColor != Color.Lime)
button.BackColor = Color.Lime;
else
button.BackColor = Color.White;
}
Then each button handler can use that same function call.
Or, if all of these buttons will always ever do exactly the same thing, then you can use one click handler function for all of them. In this case what you'd need to do is determine which button invoked the handler (whereas you're currently referencing button1 directly) so that you know which one to change. The sender object passed into the handler function is actually a reference to the form element which invoked the handler. All you need to do is cast it:
private void button_Click(object sender, EventArgs e)
{
var button = (Button)sender;
if (button.BackColor != Color.Lime)
button.BackColor = Color.Lime;
else
button.BackColor = Color.White;
}
So first the handler grabs a reference to the button which invoked it, then runs the logic on that button. Note also how I made the name of the handler function slightly more generic. Now you'd go to the form designer and set button_Click as the click handler for all of the buttons which should invoke this.

You do this the exact same way you'd do it for any C# class. You derive your own class and customize the base class behavior. Every event has a corresponding OnXxxx() method that you can override.
Add a new class to your project and paste this code:
using System;
using System.Windows.Forms;
class MyButton : Button {
protected override void OnClick(EventArgs e) {
// Your code here
//...
base.OnClick(e);
}
}
Change the code in OnClick() to do what you want to do. Compile. You'll now have your own button control on the top of the toolbox. And can drop as many copies of it as you want on a form. They'll all behave the same without having to add any code in the form.

Probably the easiest way would be to have each button invoke the same click handler. Then inside of your handler use the Sender instead of hard coding Button1.
private void buttons_Click(object sender, EventArgs e)
{
var theButton = (Button) sender;
if (theButton.BackColor != Color.Lime)
{
theButton.BackColor = Color.Lime;
}
else
{
theButton.BackColor = Color.White;
}
}

You can get the button that raised the Click event by casting sender to Button.
You can then add the same handler to every button.

I'm a VB guy.... in VB.Net you can add multiple handlers for events and connect multiple events to the same handler.
This sub hooks all clicks to color the buttons.
Private Sub ColorButtons(sender As System.Object, e As System.EventArgs) _
Handles Button1.Click, Button2.Click, ..
I do this all the time accidentally because I drag/copy a control to make a new one and the new button gets added to the original's events.
Other Subs can handle the same events to do other work - both will execute.
No idea how to do this in C#.

The proper way to do this really is to associate each button's click event to the function you have coded for that purpose (you want the function to run when the button is clicked, right?), so add the following (or similar) to an appropriate section of your code:
MyButton1.Click += new RoutedEventHandler(buttons_Click);
MyButton2.Click += new RoutedEventHandler(buttons_Click);
etc...
You can associate as many controls to the event handler as you like.

What I usually do before is this:
private void button2_Click(object sender, EventArgs e)
{
button1.PerformClick();
}
This code will just simply run the codes under button1_Click.
But try not to practice as such and just simply put it in a function/method just like what David suggested.

How to sync up to different events in Winforms

If I have a button which does something and also a double-click event on a data grid which I want to do the same thing, what is the best way to ensure that only one function has to be maintained?
Apart from doing the following, is there any fancy C# way to indicate that two events are to do the same thing?
void button1_Click(...) { MyFunction(); }
void dataGrid1_DoubleClick(...) { MyFunction(); }
void MyFunction() { // do stuff }

I suppose that you are talking about a DataGridView (WinForms) so the signature of the event DoubleClick in the DataGridView and the signature of Click event on a button control is the same.
(An EventHadler). In this case you can simply set the same method using the form designer or manually bind the event
dataGridView1.DoubleClick += new EventHandler(MyFunction);
button1.Click += new EventHandler(MyFunction);
Of course the MyFunction method should match the expected signature of an EventHandler
private void MyFunction(object sender, EventArgs e)
{
// do your work
}
Reviewing my answer after a few minutes I wish to add:
If you find yourself in a situation in which you need to differentiate between the controls using the sender object (like Control c = sender as Control; if (c.Name == "someName") ) I really suggest you to return to the first idea. Call a common method but keep the EventHandler separated for each control involved.

Using VS, in the form's designer view You can set the procedure You want to call to each control's each event in the control's properties window.
image

Just to add to what Steve said, you will want to bind these events to your function manually in the Load event of your form, instead of using the events under the lightning bolt in the properties window in the designer, like so:
private void Form1_Load(object sender, EventArgs e)
{
button1.Click += MyMethod;
dataGridView1.DoubleClick += MyMethod;
}
void MyMethod(object sender, EventArgs e)
{
//Do Stuff
}
Also, declaring a new instance of the EventHandler class has been redundant since Anonymous methods were introduced to C#, you can just point the event directly at the method as shown above.

Which pictureBox was selected? C#

I am working on a piano in C#. I have encountered a small problem.
I have a piano keyboard which, when pressed, displays the relevant note on the staff.
The notes created are stored in an array of type PictureBox, called picBox. I have constructed the following event handler, however it is not working.
private void pictureBox_Click(object sender, MouseEventArgs e)
{
picBox[0].MouseDown += new MouseEventHandler(pic_Click); //testing for first location
}
private void pic_Click(object sender, MouseEventArgs e)
{
ClickedTextBox.Text = "I was clicked";
}
I am just testing to see if the first note was clicked. Why is this not working?
Here is the method which adds the picturebox (containing the note) to the staff (panel3).
public void addPictureBox(int x, int y, Image image)
{
picBox[cnt] = new PictureBox();
picBox[cnt].Image = image;
picBox[cnt].Location = new Point(x, y);
picBox[cnt].BackColor = Color.Transparent;
panel3.Controls.Add(picBox[cnt]);
picBox[cnt].BringToFront();
cnt++;
}
What is wrong with my event handler please? Also, what can I do to identify the location in the array of the picturebox clicked? Thank you

As said in the first comment, you subscribe to the event in a wrong location.
Also use the sender parameter of your event handler to know which picturebox is clicked (it'll contain an instance of the picturebox).