Windows can be moved on the screen by dragging their title bar; they can be resized by dragging their borders. But what if our window needs no title bar / borders (or they are custom drawn)? (aka WindowStyle="None").

Introducing MoveResizeBehavior, a WPF custom behavior that can be added to any FrameworkElement will provide move and resize functionality for its parent window.

<Border DockPanel.Dock="Top" Height="11" Margin="7"
        b:MoveResizeBehaviour.ResizeWindow="Top"/>
<Border DockPanel.Dock="Bottom" Height="11" Margin="7" 
        b:MoveResizeBehaviour.ResizeWindow="Bottom"/>
<Border DockPanel.Dock="Right" Width="11" Margin="7,0" 
        b:MoveResizeBehaviour.ResizeWindow="Right"/>
<Border DockPanel.Dock="Left" Width="11" Margin="7,0" 
        b:MoveResizeBehaviour.ResizeWindow="Left"/>
<Border Height="43" VerticalAlignment="Top" 
        b:MoveResizeBehaviour.MoveWindow="True"/>

where

xmlns:b="clr-namespace:AndreiPana.WPF.Utilities"

ResizeWindow can take one of the following values: None, Left, TopLeft, Top, TopRight, Right, BottomRight, Bottom, BottomLeft, while the MoveWindow can be either True or False.

Internally, the behaviors attach to the MouseDown event, so the FrameworkElements on which they will be set better not process themselves MouseDown, otherwise it might interfere with the behaviors.

A simple and small test project showing the functionality is available on Github but, for convenience, here’s the MoveResizeBehavior.cs file that you can copy/paste to any WPF project and used it as it is: