Preset buttons in BoxModelSection / BorderEffectsSection now write through the discrete setters (setPropStyles / setPropStyle), so a keyboard-activated preset (no pointerup or focusout to close the burst) never merges into the previous edit of the same key. SpacingControl gains an optional onPreset for this; margin/padding presets are also one undo step for all four sides in the media panels. Refs #7 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>