Displaying Child forms as Modal Dialog

Question

Hi I've a parent form frmParent and a child form frmChild. I open the child form as a modal dialog from the parent form as below -- frmChild.ShowDialog(this); Now when the child form is opened I'm able to move the child form outside the parent form. Is there a way to restrict the Modal form to move within the Parent form ? Thanks

Vulpes · Answer

I've tried various approaches on my Windows 7 machine such as calling the API function SetParent and handling the dialog's LocationChanged event to ensure it stayed within the parent's bounds - but none of them would work :( What does work is to set the dialog's start position to 'CenterParent' and then handle its WndProc to intercept the SC_MOVE message and prevent it from being moved at all. If that's of interest the code is as follows: // on parent from ChildForm frmChild = new ChildForm(); frmChild.StartPosition = FormStartPosition.CenterParent; frmChild.ShowDialog(this); // on child form const int WM_SYSCOMMAND = 0x0112; const int SC_MOVE = 0xF010; protected override void WndProc(ref Message m) { switch(m.Msg) { case WM_SYSCOMMAND : int command = m.WParam.ToInt32() & 0xfff0; if (command == SC_MOVE) return; break; } base.WndProc(ref m); }

sasikumar · Answer

This was a great(differnt) approach to the problem. It worked. Thanks much.