fix(controls): Tooltips, context menu, and comboboxes drop shadow

[Nuklon]

Pull request type

Please check the type of change your PR introduces:

• Update
• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes

What is the current behavior?

Currently, the drop shadow used by tooltips and context menus are broken. This is because effects get clipped.

What is the new behavior?

The solution is to add a decorator that wraps around it. I also updated the dropshadows to follow original colors (they were far too dark). The tooltips have less shadow than context menus in WinUI.

[Nuklon]

@pomianowski best viewed without whitespace changes:
https://github.com/lepoco/wpfui/pull/1472/files?diff=split&w=1

[Difegue]

Have you considered adding this change to ComboBoxes as well?

I believe all you need is the following:
wpfui-12-20-21.patch

EDIT: Seems like wrapping the ComboBox popup in EffectThicknessDecorator breaks its animation a bit for some reason.. Might need some additional changes so feel free to ignore me 😓

[Nuklon]

Have you considered adding this change to ComboBoxes as well?

I believe all you need is the following: wpfui-12-20-21.patch

EDIT: Seems like wrapping the ComboBox popup in EffectThicknessDecorator breaks its animation a bit for some reason.. Might need some additional changes so feel free to ignore me 😓

Yes, with animations there are some issues due to added margins, and the translation gets rendered above the combobox. There are some possibilities:

1. Remove TranslateTransform of dropdown.
2. Change TranslateTransform to ScaleTransform (looks OK, but with very long comboboxes it's not as similar to WinUI).
3. Accept a slight UI clipping issue. If you use EffectThicknessDecorator with Thickness="30,0,30,30" (the shadow is only added below and to the sides of the element) the shadow clips a little below the combobox until the animation is done. This might be acceptable. This is very simple and you can basically keep all code as-is.
4. 3 and then delay adding the dropshadow. This is also done by WinUI, which only adds shadow when it's fully expanded, so I think this is the best solution.

I'll commit some changes for this.

[chucker]

Consider giving this class a doc block (explaining the purpose) that effectively repeats this part from the PR:

This is because effects get clipped. [..] The solution is to add a decorator that wraps around it.