Preferences
Customize Diagrammix3 to match your workflow through the Preferences panel.
Opening Preferences
Access preferences via:
- Diagrammix3 → Preferences... (Cmd+,)
Appearance
Theme
Choose how Diagrammix3 appears:
- System: Matches your macOS appearance (Light or Dark mode)
- Light: Always use light theme
- Dark: Always use dark theme

Canvas Settings
Grid
Configure the grid overlay on your canvas:
- Show Grid: Toggle grid line visibility
- Snap to Grid: When enabled, shapes align to grid intersections when moved or resized
- Grid Size: Adjust the spacing between grid lines (8px, 16px, 24px, etc.)
The grid helps maintain consistent spacing and alignment across your diagram.
Smart Guides
- Enable Smart Guides: When enabled, alignment guides appear as you drag objects, showing when edges or centers align with other objects
Smart guides work independently of the grid and can be used together or separately.
Rulers
- Show Rulers: Display measurement rulers along the top and left edges of the canvas
Rulers help with precise positioning and sizing of elements.
UML Settings
UML Guidance
- Enable UML Guidance: When enabled, provides suggestions and validation for UML diagrams to help ensure correct notation
This is helpful when learning UML or when diagram accuracy is important.
Default Styles
Set default appearance for new objects:
- Default Fill Color: Color applied to new shapes
- Default Stroke Color: Border color for new shapes
- Default Font: Font family for new text
These defaults apply to all new documents.
Performance
- Hardware Acceleration: Use GPU for rendering (recommended for complex diagrams)
- Smooth Scrolling: Enable for smoother canvas navigation
File Handling
- Auto-save: Automatically save changes at regular intervals
- Create Backup: Keep backup copies of your documents