WndProc WM_NCMOUSEUP no fire

Question

I've been trying to get a Form Border (title bar) mouse up for a bit now, and it seems like it's broken (I have found numerous other articles that state the same).

I have tested:

Const WM_LBUTTONUP = &H202
Const WM_MBUTTONUP = &H208
Const WM_RBUTTONUP = &H205
Const WM_NCXBUTTONUP = &HAC
Const WM_XBUTTONUP = &H20C
Const WM_MENURBUTTONUP = &H122
Const WM_NCLBUTTONUP = &HA2
Const WM_NCRBUTTONUP = &HA5
Const WM_NCLBUTTONDOWN = &HA1
Const WM_NCMOUSEMOVE = &HA0

quite thoroughly. What I am seeing is that, while WM_NCLBUTTONUP doesn't work, WM_NCLBUTTONDOWN does, and upon release (where I would expect the WM_NCLBUTTONUP), I get a WM_NCMOUSEMOVE instead. The issue being that you also get a WM_NCMOUSEMOVE as expected whenever you move the mouse outside of the client area (aka the form border)..

In a first attempt to overcome this, I have come up with:

Private MouseIsDown As Boolean = False
Protected Overrides Sub WndProc(ByRef m As Message)
    Const WM_NCLBUTTONDOWN = &HA1
    Const WM_NCMOUSEMOVE = &HA0
    If (m.Msg = WM_NCLBUTTONDOWN) Then
        MouseIsDown = True
        Console.WriteLine("NCLButtonDown")
    ElseIf (m.Msg = WM_NCMOUSEMOVE) Then
        If MouseIsDown Then
            Console.WriteLine("NCMouseMove" + Environment.NewLine + "LParam: " + m.LParam.ToString() + Environment.NewLine + "WParam: " + m.WParam.ToString() + Environment.NewLine + "Res: " + m.Result.ToString())
            MouseIsDown = False
        Else
            Console.WriteLine("Not mouseup")
        End If
    Else
    End If
    MyBase.WndProc(m)
End Sub

This seems to be working through initial testing, but I am curious if this would be appropriate, or if there is a message that I am simply missing (I have looked through: http://www.pinvoke.net/default.aspx/Constants.WM quite closely though, and don't see anything else that looks right).

WndProc WM_NCMOUSEUP no fire

1 Answers