Home/ Questions/Q 6897281
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-27T07:08:57+00:00

I have a borderless WPF window (WindowStyle=None) that can be moved by catching LeftMouseDown

  • 0

I have a borderless WPF window (WindowStyle=”None”) that can be moved by catching LeftMouseDown and then call DragMove. That works fine.

However, I want to prevent any part of the window from leaving the screen area.
I catch the LocationChanged but that is called AFTER the window has already moved and thus any changes to the windows position I make in that event cause the window to jump back, which looks very unprofessional.

Is there an event I can catch that is fired BEFORE the window is actually moved.
I tried MouseMove and PreviewMouseMove but they don’t get fired during DragMove.

This stuff works fine with WinForms.

Does anybody have a solution for this or is this just due to the half-baked nature and state of WPF?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    I didn’t get the CoerceValueCallback approach to work (if anybody has a solution for this approach please share it).

    My solution:
    Intercept WM_WINDOWPOSCHANGING message in a WPF WndProc. The solution is a bit long to post here, but here are 2 links that put me on the right track:

    How to handle WndProc messages in WPF?
    (There were a few nay-sayers in this link that stated that WndProc would not work with WPF.
    I can’t comment on the statement in that general fashion but in this particular case it works like a charm.)

    http://huddledmasses.org/wpf-windows-that-snap-to-screen-edges/

    Put body of OnPreviewPositionChange in WndProc.

    • 0