WIP MetroWindow: OverlayFadeIn / OverlayFadeOut

[punker76]

What changed?

• New OverlayFadeIn and OverlayFadeOut properties to set/override the overlay fade in/out Storyboards which are used for the Dialogs
• Fix the fade in and out animation if no duration exists
• Fix HideMetroDialogAsync which sometimes fails to close dialog (async call order)

Closed issues.

Closes #2825
Closes #3022

[GF-Huang]

Hi @punker76 , is there an example for using OverlayFadeIn and OverlayFadeOut ?
I want to make the CustomDialog show animation shorter but not disabled.

[punker76]

@greatfirewall OverlayFadeIn and OverlayFadeOut are properties at the MetroWindow, so simply set a new Storyboard and it will use it.

Here are the 2 standard Storyboards

MahApps.Metro/src/MahApps.Metro/Themes/MetroWindow.xaml

Lines 543 to 556 in 3b72bce

	<Storyboard x:Key="OverlayFastSemiFadeIn"
	AccelerationRatio=".97"
	BeginTime="0:0:0"
	SpeedRatio="2.7"
	Storyboard.TargetProperty="Opacity">
	<DoubleAnimation To=".7" />
	</Storyboard>
	<Storyboard x:Key="OverlayFastSemiFadeOut"
	AccelerationRatio=".97"
	BeginTime="0:0:0"
	SpeedRatio="2.7"
	Storyboard.TargetProperty="Opacity">
	<DoubleAnimation To="0.0" />
	</Storyboard>

[GF-Huang]

@punker76 thanks.

[GF-Huang]

I had try change the AccelerationRatio and SpeedRatio but no effect.
So should I add a Duration attribute ?

[punker76]

@greatfirewall And you did set the new Storyboards to the both propetries?

[GF-Huang]

Sorry my fault, now works well. :)