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How could I make textbox 1 change the font size of the text in textbox 2. similar to changing font size in google docs or Microsoft word

So I have 2 text boxes, one of them for writing in and one of them for changing the font size, how could I make the font size text box make the font size in the writing text box change?

Well for starters, assuming it is a Windforms app with 2 textbox objects named `textBox1' and 'textBox2' respectively, it isn't so difficult to rig up a quick way to to this.
First, in your forms load event you need to set the initial value of textBox2
private void Form1_Load(object sender, EventArgs e)
{
textBox2.Text = textBox1.Font.Size.ToString();
}
then, from there you just need to create a TextChanged event for textBox2 either by double clicking the textBox2 object(in visual editor) or selecting the event from the events creator.
Finally, to handle the event in a quick and easily broke down fashion for beginners:
private void textBox2_TextChanged(object sender, EventArgs e)
{
//use try/catch incase user inputs invalid value and cannot parse it as a float
try
{
//Cannot set the Size value of a font, so create a new font with desired size, referencing currrent textBox1.Font properties,
textBox1.Font = new Font(textBox1.Font.FontFamily.ToString(), float.Parse(textBox2.Text), textBox1.Font.Style, textBox1.Font.Unit, textBox1.Font.GdiCharSet, textBox1.Font.GdiVerticalFont);
//It worked, textBox2 background color stays white to signify success.
textBox2.BackColor = Color.White;
}
catch (Exception)
{
//An exception was thrown parsing input, set textBox2 background to red so user knows this is invalid.
textBox2.BackColor = Color.Red;
}
}

Change button background color on click in c sharp windows application

I need to change the button background color by itself, that means when I will click on a button then it should change the background color, but when I will click again on the same button then I need to back default button color
I have tried on this event method
private void slot_1(object sender, RoutedEventArgs e)
{
//SlotLogic();
slot1.Background = Brushes.Green;
}
private void slot_2(object sender, RoutedEventArgs e)
{
//SlotLogic();
slot2.Background = Brushes.Green;
}

1 - You specified Windows Application. That's kind of broad. I believe you mean Windows Forms?
2 - You're also not checking whatsoever the current state of the button, so I'm not sure how do you think that clicking on the same button twice would have a different result, since you are executing the exact same come twice slot1.Background = Brushes.Green;.
Windows Forms
private bool isSlot_1Clicked = false;
private void slot_Click(object sender, EventArgs e)
{
if (isSlot_1Clicked)
slot.BackColor = Color.Green;
else
slot.BackColor = Color.Red;
isSlot_1Clicked = !isSlot_1Clicked;
}
If you want to have a toggle logic, you need to check the current state to inverse it. There is a lot of ways to do it, I choose to store it on a separate variable isSlot_1Clicked for sake of simplicity.
You could also check the slot's button background color, or check a complex object's property, or an array, and so on.
The first lines of code just checks the current state of the variable, and changes the button's background accordingly. The last line just set the variable isSlot_1Clicked to the inverse of it, executing the essence of the toggle logic.
WPF Version
private Brush slot_1DefaultBackground = null;
private void Slot1_Click(object sender, RoutedEventArgs e)
{
// store the default background value
if (slot_1DefaultBackground == null)
slot_1DefaultBackground = slot1.Background;
// check the current background, and toggle accordingly
if (slot1.Background != slot_1DefaultBackground)
slot1.Background = slot_1DefaultBackground;
else
slot1.Background = Brushes.Green;
}
This version stores the default button's background, and checks the current background against it to execute the toggle logic.

Using MouseHover event and ToolTip

To show the relevant information(in monopoly game, the property belongs which player, current market price etc.), I put a Label on the top of a panel, and used a ToolTip object to display the information. This is the image of my current setup.
Here are the steps I have done:
1.Added MouseHover event handler (The Label name is MEDITERANEAN)
this.MEDITERANEAN.MouseHover += new System.EventHandler(this.MEDITERANEAN_MouseHover);
2.Initialized Tooltip
private void InitializeToolTip()
{
toolTipLabel.ToolTipIcon = ToolTipIcon.Info;
toolTipLabel.IsBalloon = true;
toolTipLabel.ShowAlways = true;
}
3.Call setToolTip() in MouseHover call back function
private void MEDITERANEAN_MouseHover(object sender, EventArgs e)
{
toolTipLabel.SetToolTip(MEDITERANEAN, "You put mouse over me");
rolledDice.AppendText("Mouse Over");
}
But when I start application and move my cursor over the label, there is no text from toolTipLabel. What part did I make mistakes?
Interestingly, i made other function and it works.
private void panelBoard_MouseOver(object sender, EventArgs e)
{
toolTipLabel.SetToolTip(panelBoard, "You put mouse over me");
rolledDice.AppendText("Mouse Over");
}

I think you just need to bring your lable control in front of image. Try something like this .
MEDITERANEAN.BringToFront();

I found the solution, first I should set Panel's property "Enable" to true, then set label's property "visible" to true as well.

How to disable cursor in textbox?

Is there any way to disable cursor in textbox without setting property Enable to false?
I was trying to use ReadOnly property but despite the fact that I can't write in textbox, the cursor appears if I click the textbox. So is there any way to get rid of this cursor permamently?

In C#, you can use the following read-only textbox:
public class ReadOnlyTextBox : TextBox
{
[DllImport("user32.dll")]
static extern bool HideCaret(IntPtr hWnd);
public ReadOnlyTextBox()
{
this.ReadOnly = true;
this.BackColor = Color.White;
this.GotFocus += TextBoxGotFocus;
this.Cursor = Cursors.Arrow; // mouse cursor like in other controls
}
private void TextBoxGotFocus(object sender, EventArgs args)
{
HideCaret(this.Handle);
}
}

In C# you can disable the cursor in a textbox by temporarily disabling and then re-enabling the text box whenever it receives the focus. Note there is no need to make the textbox read only if using this method. For example:
private void TextBox_Enter(object sender, EventArgs e)
{
TextBox.Enabled = false;
TextBox.Enabled = true;
}

You could use a Label instead. When in the designer, you set BorderStyle = Fixed3D, BackColor = Window and AutoSize = False, it looks a lot like a TextBox.
However, the cursor in a TextBox is provided so that the user can scroll through the text when it is longer than the box. You'll lose that functionality with a Label, unless you are sure that it will always fit. Other than that, it is not possible to remove the cursor from a TextBox.

Putting the hideCaret function inside the TextChanged event will solve the problem:
[DllImport("user32.dll")]
static extern bool HideCaret(IntPtr hWnd);
private void textBox1_TextChanged(object sender, EventArgs e)
{
HideCaret(textBox1.Handle);
}

Easiest solution for me was to just override the on focus event and focus back to the parent. This prevents the cursor and any editing of the textbox by the user and basically disables the text box with out having to set the Enabled = false property.
private void Form1_load(object sender, EventArgs e) {
textBox1.ReadOnly = true;
textBox1.Cursor = Cursors.Arrow;
textBox1.GotFocus += textBox1_GotFocus;
}
private void textBox1_GotFocus(object sender, EventArgs e) {
((TextBox)sender).Parent.Focus();
}

Like #Mikhail Semenov 's solution, you can also use lambda express to quickly disable the cursor if you do not have many textboxes should do that:
[DllImport("user32.dll")]
static extern bool HideCaret(IntPtr hWnd);
textBox1.ReadOnly = true;
textBox1.BackColor = Color.White;
textBox1.GotFocus += (s1, e1) => { HideCaret(textBox1.Handle); };
textBox1.Cursor = Cursors.Arrow;

You can set it programatically.
textBox1.Cursor = Cursors.Arrow;

This is not strictly an answer to the question, but perhaps it can solve some similar problem(s). I use a textbox control which can look like a label for a control which displays a scale, but can be edited, when clicked. Start enabled = false and make an activation (enabled = true) in a mousehandler of the parent of the textbox control (which, when disabled, border None and backcolor = parent backcolor, looks like a label). E.g. when enter hit or other event, disable again in KeyDown handler.
(Of course the parent mouse click routine can check whether the mouseclick really occured in the label/textbox control).
If you need the textbox control to activate by tabbing, some more work is required (than I have done).
I use the form constructor to find the textbox parent at runtime and to apply the delegate mouse control. Perhaps you can do this as wel in compile time (Form header), but that seemed a little error-prone to me.

One way of doing it is using View + TabIndex, you can do indexing of some other controls on the dialog as first, let say for buttons if there any. Then as if the control tabIndex is not the first i.e 0, cursor won't get appear there.

To disable the edit and cursor in the TEXT BOX
this.textBox.ReadOnly = true;
this.textBox.Cursor = Cursors.No;//To show a red cross icon on hover
this.textBox.Cursor = Cursors.Arrow //To disable the cursor

you can use RightToLeft Property of Text Box, set it to true, you will not get rid of the Cursor, but it will get fixed at right corner and it will not appear automatically after every text you type in your text Box. I have used this to develop an application like Windows Calculator.

Suppress backspace, delete keys in MaskedTextbox

The question is simple: how to do it?
I've a couple of MaskedTextboxes which are filled by some indirect user actions (so not by typing in values directly). The text within the textboxes is colored red when the input is being rejected by the mask. Fine so far.
However, I don't want the end-user to be able to edit the boxes directly. So, I added the following code:
private void HandleMaskedTextBoxKeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = true;
}
private void HandleMaskedTextBoxKeyDown(object sender, KeyEventArgs e)
{
e.Handled = true;
e.SuppressKeyPress = true;
}
And while most characters are handled, the backspace and delete keys aren't: text disappears when pressing those keys. How can those keys be handled, too?
(Another option would be to set the readonly property of the boxes to true, but then the text doesn't get colored red anymore when input is rejected. I tried to force the red color in the MaskInputRejected event, but this didn't work out, either.)

I think it's a good idea to set the MaskedTextBox's ReadOnly property to true. But instead of handling the MaskInputRejected event, you should use the TypeValidationCompleted event like this:
private void maskedTextBox1_TypeValidationCompleted(object sender, TypeValidationEventArgs e) {
maskedTextBox1.ForeColor = e.IsValidInput ? Color.Black : Color.Red;
}
Since I guess you're modifying the value of the MaskedTextBox by code, you'll have to also handle the TextChanged event to trigger a validation like this:
private void maskedTextBox1_TextChanged(object sender, EventArgs e) {
maskedTextBox1.ValidateText();
}
Finally (and this is key), since the MaskedTextBox will be read only, you'll want to set the BackColor and ForeColor properties back to Color.White and Color.Black respectively, but you'll have to do it in code, in the constructor of the form for instance...
maskedTextBox1.BackColor = Color.White;
maskedTextBox1.ForeColor = Color.Black;
If you have a lot of them, I suggest you create a new control that inherits from MasketTextBox and override those values.

You can use a richtextbox. Set read only to true, and mask the chars with the code beind.
I hope that helps.
RG