'Autosized' SWindow with `.AutoHeight()` elements has unwanted white space

Heavily discussed and diagnosed in this thread: [Link Removed]

[Link Removed] narrowed down the cause:

It's the calculation inside the SWindow that is wrong, sometime. It adds SWindowDefs::DefaultTitleBarSize in SWindow::GetWIndowSizeFromCientSize
I am not sure how to prevent that in all the cases.

1. Create a new slate window using the following code:

   TSharedRef<SWindow> MyWindow = SNew(SWindow)
   	.SizingRule(ESizingRule::Autosized)
   	.SupportsMaximize(false)
   	.SupportsMinimize(false)
   	.MinHeight(0.f)
   [
   	SNew(SVerticalBox)
   	+ SVerticalBox::Slot()
   	.AutoHeight()
   	[
   		SNew(SButton).Text(NSLOCTEXT("UnrealEd", "OK", "OK"))
   	]
   	+ SVerticalBox::Slot()
   	.AutoHeight()
   	[
   		SNew(SButton).Text(NSLOCTEXT("UnrealEd", "OK", "OK"))
   	]
   	+ SVerticalBox::Slot()
   	.AutoHeight()
   	[
   		SNew(SButton).Text(NSLOCTEXT("UnrealEd", "OK", "OK"))
   	]
   	+ SVerticalBox::Slot()
   	.AutoHeight()
   	[
   		SNew(SButton).Text(NSLOCTEXT("UnrealEd", "OK", "OK"))
   	]
   	+ SVerticalBox::Slot()
   	.AutoHeight()
   	[
   		SNew(SButton).Text(NSLOCTEXT("UnrealEd", "OK", "OK"))
   	]
   ];
   FSlateApplication::Get().AddWindow(MyWindow);
   

2. Launch UE and bring up the new window.

RESULT: There's unexpected white space at the bottom of the window: [Link Removed]

EXPECTED: The window fits its contents tightly, without the added whitespace at the bottom: [Link Removed]