On Windows 8 a window with height 23px resizes to 39px after dragging

[digimezzo]

I've bumped into a peculiar issue. I've written a small application which demonstrates it: https://www.dropbox.com/s/jndzb2f5ctf8ulf/Mahapps_WindowHeight_Issue.zip?dl=0

This demo application is using MetroWindow (Mahapps Metro 1.1.2) and has a window height=23px when it starts. If you reposition the window by dragging with the mouse, the window height jumps to 39px by itself.
This issue doesn't happen on windows 7, but it does on windows 8. Useful to know: it happens on windows 8 when the performance options are configured as "adjust for best appearance", it doesn't happen when they're configured as "adjust for best performance".

Also useful: 39px is the minimum window height possible when a window has a WindowStyle (I have not found any docs on that, but discovered it by trial and error). A height lower than 39px can only be achieved when WindowStyle=None.

Could it be that dragging the window suddenly restores the WindowStyle?

Edit: I've pinpointed the performance setting which causes this: "Animate windows when minimizing and maximizing"

[punker76]

Here some Infos about this issue:

• MahApps use always WindowStyle="None" (it is explicit set in BorderlessWindowBehavior
• MahApps enhanced the WindowChrome and WindowChromeWorker to achieve the animation of the window itself together with the WindowStyle="None" setting
• This causes the window height issue
• The BorderlessWindowBehavior has now a fix to solve this
• It's recommended to set always the MaxHeight too!

A sample

<controls:MetroWindow x:Class="MainWindow"
                      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                      xmlns:controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
                      Title="MainWindow"
                      BorderThickness="0"
                      Height="23"
                      MaxHeight="23"
                      TitlebarHeight="23"
                      ShowTitleBar="False"
                      IsWindowDraggable="True"
                      Background="Wheat"
                      Width="400"
                      ResizeMode="CanMinimize">
    <Grid />
</controls:MetroWindow>