Ok, dia is totally screwed up with units… here’s how to make it work well.
File -> Preferences
User Interface length unit: Centimeter Font-size unit: Point Diagram Defaults Portrait Paper type: Letter Connection Points: Visible Snap to object View Defaults Width: 800 Height: 600 Magnify: 100 Page breaks: uncheck "Visible" Antialias: uncheck "view antialiased" Grid Lines Visible Snap to uncheck Dynamic grid resizing X Size: 1.0 Y Size: 1.0 Lines per major line: 5
on the diagram window… File->Page Setup
Paper Size: Letter orientation again portrait Margins 2.54cm all around Scale: 100.0
This results in a window with 100x100pixel gridlines (when exported as png w/ or w/o alpha)
results in 5cmx5cm grids when exported directly to pdf