PR: GTK4 Migration & Standalone Support for Calculate Activity

[DeepaliSingh-git]

Migrated the Calculate activity from GTK3/Sugar3 to GTK4/Sugar4, adding full standalone execution support. Core functionality is preserved, the UI is modernized, and the activity now runs both inside and outside Sugar seamlessly.

What’s Changed

Core Migration

• Migrated to GTK4 with Sugar4 imports and fallback support.
• Introduced append_toolbar() for cleaner toolbar management.
• Introduced minimal fallback components to simulate sugar4 APIs
• Added GTK4 compatibility shims for:
  • Toolbars, separators, and event boxes
  • Entry text insertion
  • Box packing/reordering

Compatibility

• Works standalone
• Runs inside Sugar4 if available
• GTK4 required and fully functional

Known Limitations

• Not compatible with current Sugar (GTK3-based)
• Fallback widgets are minimal and do not fully replicate Sugar behavior
• Visual differences may exist due to absence of Sugar theme

Testing

Tested on Fedora Linux 42 (WSL) with GTK4:

GDK_BACKEND=x11 python3 main.py

calculate-activity.mp4