Feature request: Text selection / copy/paste in the TextField

[celer]

As a user I want to be able to select text in the TextField, to copy / paste, ideally selection will support double clicking to select contiguous selection of text. This should copy / paste text to the OS clip board.

For the password box, only paste should work - you should not be able to copy a password out of a password field.

[kolkov]

Thanks for the feature request @celer!

Good news — most of this is already implemented internally:

Already working:

• Click-drag text selection with visual highlight
• Double-click word selection
• Shift+click to extend selection
• Ctrl+A (select all), Ctrl+C (copy), Ctrl+X (cut), Ctrl+V (paste)
• Shift+arrows for selection extension
• Ctrl+Left/Right for word-level navigation

What's missing (the actual gap):

• System clipboard integration — currently uses an internal widget-local clipboard (copy/paste only works within the same widget instance, not to/from OS clipboard). The platform APIs exist in gogpu (PlatformProvider.ClipboardRead/Write), they just need to be connected to the TextField widget via a ClipboardProvider interface extension on widget.Context.
• Password paste-only mode — TypePassword already masks text visually, but doesn't prevent copying. A simple guard clause in handleCopy() is needed.

Estimated effort: ~3 hours for system clipboard integration + password restriction. We'll prioritize this.