Add option to enable/disable WS_CLIPCHILDREN window style

[amrbashir]

While working on tauri-apps/wry#1041 which allows adding the webview as a child window, I noticed that when setting the webview to be transparent, the portion of the parent behind it doesn't render properly and that was because of WS_CLIPCHILDREN

• Tested on all platforms changed
• Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality
• Updated feature matrix, if new features were added or implemented

[notgull]

Why was WS_CLIPCHILDREN added in the first place? I'm at the gym right now so I can't do an in depth blame.

[msiglreith]

This will break child rendering in non-special cases. The parent window can now overdraw the child window.

[amrbashir]

Would it make more sense to make this configurable? and what should the default behavior be?

[msiglreith]

I would prefer to avoid adding a config for this as it just increases the api surface - I can try to look a bit at the weekend if there is a better solution, atm unsure how alpha blended composition is done in detail here to achieve the desired effect

[msiglreith]

After trying various options¹, getting the compositor to alpha blend a child window is quite a challenge.. unsure if it's possible in a generalized way. Therefore I'm currently leaning towards a backend specific option to disable certain style flags.

Footnotes

1. I managed to freeze my system completely with one approach involving WS_EX_LAYERED in a reproducible way.. ↩

[kchibisov]

If that will be the resolution, I'd probably suggest to put this thing on hold, until better days/0.30.0.

[amrbashir]

Therefore I'm currently leaning towards a backend specific option to disable certain style flags.

I will add that once I get some time, but should WS_CLIPCHILDREN be present by default and disabled by the platform specific API or the other way around?

[msiglreith]

Thanks, WS_CLIPCHILDREN should be enabled by default.

[amrbashir]

alright, should be good to go now.