The GMAT GUI lays out controls that are sometimes centered on the panels, and sometimes left-aligned. Five representative examples are attached to this ticket. This is a bit distracting in the Linux GUI because the MDI interface is implemented as tabbed views, so some panels (SNOPT, upper half of GroundStation) are left aligned and others (ImpulsiveBurn, Formation, PropSetup) are centered.
Screen snaps from Linux are attached. I suspect that maximizing Windows panels will also show this inconsistency, but I haven';t checked that piece.