In my RCP application, I'm trying to use the Eclipse preferences dialog. I'm adding extensions to the "org.eclipse.ui.preferencePages" and preparing related IWorkbenchPreferencePage implementations. My preference page names are a bit long, so that they are not totally visible on the left side tree of the preferences dialog. Dragging the sash bar to the right increases the width of this tree, but it is resetted after the program is closed and reopened. Is it possible to increase the default width of this tree?