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I would like to prevent scrolling in comboboxes when the mouse is over the combobox (mouse over). I have already tried the following solution, but it only stops scrolling in the combobox when it is expanded.

C# - how do I prevent mousewheel-scrolling in my combobox?

br0ken.pipe
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  • What is the type of your project? The linked project is wpf, but you use the winforms tag here. – 大陸北方網友 Feb 05 '21 at 07:45
  • It's a plain Windows Forms App but the answer is also working for UserControls in Winfroms (https://stackoverflow.com/a/1883072/5586390) – br0ken.pipe Feb 05 '21 at 08:05
  • I tested it, and it works(combobox is not expanded). What is the `UserControls` in your comment? – 大陸北方網友 Feb 05 '21 at 08:13
  • Did you add the event handler? It's not listed in the PropertyGrid (it's set to `[Browsable(false)]`). You have to add it manually, in the Constructor of the Parent's Form (or whatever other Window is hosting it). Can you show what you did? – Jimi Feb 05 '21 at 08:41

2 Answers2

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You will need to extend the ComboBox control, and surppress the MouseWheel message.

Something like this:

public class ComboBoxEx : ComboBox
{
    protected override void WndProc(ref Message m) 
    {
        if (m.Msg == 522 /* WM_MOUSEWHEEL */) 
        {
            return;
        }

        base.WndProc(ref m);
    }
}
D.Kastier
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 public static void Combo_MouseWheel(object sender, MouseEventArgs e)
        {
            ComboBox cmb = (ComboBox)sender;
            if (!cmb.DroppedDown)
            {
                ((HandledMouseEventArgs)e).Handled = true;
                //this.Focus();
            }
        }
MAGA Computers
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