Bug 94674 [Preferences] Preferences dialog separator under Title for pages does not stretch all the way across
The separator under the Header title for a preference page should stretch from the border of the sash to the far right with no margins in between.
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
} finally {
					viewer.addPostSelectionChangedListener(this);
				}
			}
			public void selectionChanged(SelectionChangedEvent event) {
				Object selection = getSingleSelection(event.getSelection());
				if (selection instanceof IPreferenceNode) {
					if (!isCurrentPageValid()) {
						handleError();
					} else if (!showPage((IPreferenceNode) selection)) {
						
						handleError();
					} else {
						
						lastSuccessfulNode = (IPreferenceNode) selection;
					}
				}
			}
		});
		((Tree) viewer.getControl()).addSelectionListener(new SelectionAdapter() {
			public void widgetDefaultSelected(final SelectionEvent event) {
				ISelection selection = viewer.getSelection();
				if (selection.isEmpty())
					return;
				IPreferenceNode singleSelection = getSingleSelection(selection);
				boolean expanded = viewer.getExpandedState(singleSelection);
				viewer.setExpandedState(singleSelection, !expanded);
			}
		});