Register editing methods:
1. Inline editing on the schematic:
- Hover over register (highlights), click - input appears
- Enter hex value, press Enter or click anywhere
- Esc to cancel
2. Register and Value panel:
- Select register from dropdown (arrows or click)
- Enter value in input field
- +/- buttons for step changes
- Press Enter to apply
- Esc discards the typed value, clears the fields, and releases focus
3. Keyboard navigation:
- Tab / Shift+Tab - next/previous register on schematic
- Ctrl+Up/Down - between register rows
- Ctrl+Left/Right - between registers in a row
All changes are tracked in Undo history (Ctrl+Z).