Provide means for app to indicate that an application requires attention

### What is the problem or limitation you are having?

A way for application to request user attention, such as flashing the taskbar icon or bouncing or shaking it.

### Describe the solution you'd like

On Windows some apps does something like flashing the red icon in the taskbar. That is Form.Activate.

On macOS it's the icon bouncing. This is https://developer.apple.com/documentation/appkit/nsapplication/requestuserattention(_:)?language=objc

On GTK+ it's like an icon shaking... like when you do ``open `` in a terminal but there's a huge bunch of windows on top... a cursory search suggests ``gtk_window_set_urgency_hint``?

Qt: ``QApplication::alert``.

### Describe alternatives you've considered

Do nothing

### Additional context

_No response_

Start by comparing the platform APIs named in the issue: Windows Form.Activate, macOS requestUserAttention, GTK+ gtk_window_set_urgency_hint, and Qt QApplication::alert. Done means the application has a consistent way to request user attention across the supported desktop backends.

Written by the indexing model from the issue text.