v0.9.20

• Fixed that scrolling with mouse wheel doesn't work when a ScrollViewerEx with disabled scroll bar visibility is in another scrollable ScrollViewerEx.
• Fixed the border of a Button gets ugly when its height went too much.
• Fixed a crash when clicking maximize button with its window ResizeMode = CanMinimize.
• Added 'FlyoutOpeningMode' property to AppBarButton, AppBarRepeatButton and DropDownButton to control how the flyout can be opened automatically
• Uploaded a missing folder 'Win32'.