How to disable Hover-Messages in .NET List/TreeViews?
I have a Windows Forms application that uses some Application.Idle handlers to change the status of controls on the form.
After I added a ListView to the form I realized the Idle-Handlers get called way too often when the mouse cursor is over the ListView. By using Spy++ I saw that when the mouse cursor is over the control (not moving) the control receives WM_MOUSEHOVER messages over an over which in turn triggers the idle event 开发者_如何学运维(after the message queue is empty). The same holds for TreeView-Controls.
I wonder how I can disable this behavior?
Running this code from the command prompt will show what I mean:
using System;
using System.Windows.Forms;
public class IdleTest {
public static void Main() {
Application.Idle += delegate {
Console.WriteLine(
DateTime.Now.ToString() + " idle!" ) ;
};
Form f = new Form(){ Width=300 };
f.Controls.Add(new ListView(){ Left=0, Width=100 } );
f.Controls.Add(new TreeView(){ Left=100, Width=100 } );
f.Controls.Add(new TextBox() { Left=200, Width=100 } );
Application.Run(f) ;
}
}
You could try and override the WndProc method in your form. Then using the cursor position to filter when you do and do not want to handle the WM_MOUSEHOVER message.
Something like this:
public partial class MyForm: Form
{
private const int WM_MOUSEHOVER = 0x02A1;
protected override void WndProc(ref Message message)
{
Point mousePosition = this.PointToClient(Cursor.Position);
if ((message.Msg == WM_MOUSEHOVER) && (<useTheMousePositionToDoSomeFiltering>))
{
return;
}
base.WndProc(ref message);
}
}
EDIT: Just though of something, it might be better to create a custom ListView & TreeView (by simply deriving the built in .NET ones) and then override the WndProc routine in the new controls to always exclude WM_MOUSEHOVER.
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