Per http://help.eclipse.org/indigo/index.jsp?topic=%2Forg.eclipse.platform.doc.isv%2Freference%2Fapi%2Forg%2Feclipse%2Fswt%2Flayout%2FGridData.html GridData.FILL_{VERTICAL,HORIZONTAL,BOTH} is not recommended
Move ColorThemeManager construction to inside the Eclipse init function. This prevents it from being constructed before it's ready to use
Move the link on the preference page to below the list of themes