Strange order of events in ListView with MultiSelect set to false

[crypto_rsa]

I noticed a weird behaviour in ListView. When its MultiSelect property is set to true and I press a mouse button while the cursor is inside the control, I get a MouseDown event. Then I release the button and get a MouseUp event, just as I would expect. However, when I set the MultiSelect property to false and press a mouse button, I suddenly get the MouseUp event immediately after the MouseDown one. When I then actually release the button, no MouseUp fires. Is this intentional? How can I then properly determine when the mouse button was actually released?

[RaviBee]

Can you check the control's MultiSelect property in your mouse event handlers? /ravi

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[DaveyM69]

I can confirm what you are experiencing - this only occurs when the control itself is clicked. When a ListViewItem is clicked (MouseDown) the behaviour is normal (even if the mouse is moved away from the clicked item). Very odd. :confused:

Dave

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Binging is like googling, it just feels dirtier. Please take your VB.NET out of our nice case sensitive forum.(Pete O'Hanlon)
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

[DaveyM69]

This is a semi-solution. Subclassing the ListView and overriding WndProc, listen for the left mouse button up message and raise the MouseUp event passing the correct parameters. With a bit more work you may be able to use a flag to allow/disallow MouseUp messages to supress the erroneous one that you are getting.

public class FixedListView : ListView
{
    private const int WM\_LBUTTONUP = 0x0202;

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM\_LBUTTONUP)
        {
            // adjusting as X and Y are 16 bits each of LParam
            Point point = new Point(((int)m.LParam) & 0x0000FFFF, (int)m.LParam >> 16);
            OnMouseUp(new MouseEventArgs(MouseButtons.Left, 1, point.X, point.Y, 0));
            return;
        }
        base.WndProc(ref m);
    }
}

WM_LBUTTONUP Message[^]

Dave

If this helped, please vote & accept answer!

Binging is like googling, it just feels dirtier. Please take your VB.NET out of our nice case sensitive forum.(Pete O'Hanlon)
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

[crypto_rsa]

Yes, that's true, unfortunately I need to properly handle all clicks in the control, not just those on a ListViewItem. It even doesn't work on a ListViewSubItem.

[johannesnestler]

It works on sub items if you set FullRowSelect to true... wired bahavior...

[crypto_rsa]

Thanks for the proposed semi-solution. I put together different pieces and came up with this solution which seems to do what I want :) First, I leave the MultiSelect property set to false and set FullRowSelect to true. Then I use this code:

public class CustomListView : ListView
{
public CustomListView()
{
InitializeComponent();
}

bool fakeMouseUp = false;
bool mouseDownOnItem = false;

protected override void OnMouseDown( MouseEventArgs e )
{
	// if we're not on an item or subitem, we will get OnMouseUp immediately
	mouseDownOnItem = HitTest( e.Location ).Item != null;

	Debug.WriteLine( "OnMouseDown" );

	base.OnMouseDown( e );
}

protected override void OnMouseUp( MouseEventArgs e )
{
	if( mouseDownOnItem || fakeMouseUp )
	{
		Debug.WriteLine( "OnMouseUp" );

		mouseDownOnItem = false;
		fakeMouseUp = false;

		base.OnMouseUp( e );
	}
}

protected override void WndProc( ref Message m )
{
	if( !mouseDownOnItem && m.Msg == 0x0202 /\*WM\_LBUTTONUP\*/ )
	{
		// send a fake MouseUp event
		fakeMouseUp = true;
		Point point = new Point( ((int) m.LParam) & 0x0000FFFF, (int) m.LParam >> 16 );
		OnMouseUp( new MouseEventArgs( MouseButtons.Left, 1, point.X, point.Y, 0 ) );
	}

	base.WndProc( ref m );
}

}

But I always have a feeling of wasted time when I need to do such workarounds for weird .NET behaviour. Why on Earth do I get a MouseUp event when the mouse button was not physically released? :confused: