To open the Preferences window:
Choose Command ⌘+, comma
or pressGeneral preferences
Use the General tab in the Preferences window to choose whether Pixelmator will or will not show the Welcome screen on startup.
Also specify what the New Image contents should be: white or transparent.
Change option Hide unnecessary palettes when using adjustments or filters to reveal palettes while adjusting image.
Show action tooltips will show tooltips over image when tool without palette was used.
Show information labels will show tooltips near the cursor while drawing, selecting or resizing action is ongoing.
You can customize the transparency look using the Transparency tab in Preferences. You can choose a small, medium, or large grid size or choose a light, medium, or dark grid color.
Rulers
In the Rulers tab you can change rulers measurement units and also guides, slices and grid color.
Learn more...
Updates
You can set up Pixelmator to check whether there are any updates available. Select the Updates tab in Pixelmator’s Preferences and check the box that says “Notify me when a new version of Pixelmator is available.”