Maximize button only displays partially when using SaveWindowPosition

[ghost]

reproducable in 0.14 and 0.15.0 ALPHA41

Create a basic MetroWindow and set SaveWindowPosition to true.
Include at least the Controls (<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />). Launch the application and now maximize the window. Note that the maximize button looks correct (like this):

Close the application (while it is maximized) and launch it again (so it opens maximized).
The maximize button now looks like this:

If you change the window mode and then restore to maximum size, the icon will display correctly again.
It only happens when SaveWindowPosition is set to true and the window's last state was maximized.

Using WindowState="Maximized" on the other hand works correctly (also in conjunction with SaveWindowPosition).

[grokys]

Some information I found investigating:

This problem is caused by the fact that the contentPresenter in PART_Max is starting with a size of 9,9 where it needs to be 10,10. Restoring the window leaves it at 9,9, but that's not a problem as the Maximize icon fits that size - maximizing again resets it to its correct value of 10,10

It appears that MaxPath is being measured incorrectly- it's DesiredSize is reporting 10,10 but contentPresenter's DesiredSize is 9,9.

A workaround could be to set MaxPath's Width and Height explicitly:

<Path x:Name="MaxPath" SnapsToDevicePixels="True" Width="10" Height="10" Fill="{Binding Path=Foreground, RelativeSource={RelativeSource AncestorType=Button}}" />

Or in the trigger that sets the Path.Data.

Let me know if this is an acceptable solution and I will prepare a pull-request.

[ghost]

Yeah, you are right, it does fix it.

I don't know whether MahApps supports radical restyling to the point where the maximize button would be of a totally different size, but for all the default styles (which are just different colors) it works without issues.