Bug 81983 [preferences] Disabling and enabling folding on small file takes forever
3.1 M4 Using enable/disable folding on a small CU takes forever. This is caused by the recent change to apply the preference to all Java editors. In another (hidden) window (Debug) I had StyledText open which (understandably) took long to react on the preference change. Non-visible editor's should not react to this change until they become visible.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
}
					} else {
						viewer.setSelectedRange(selection.x, 1);
						viewer.doOperation(ISourceViewer.FORMAT);
					}
				} catch (BadLocationException exception) {
					
				} finally {
					viewer.setRedraw(true);
					viewer.restoreSelection();
				}
			}
		}
	}
	
	/**
	 * Internal activation listener.
	 * @since 3.0
	 */
	private class ActivationListener extends ShellAdapter {
		/*
		 * @see org.eclipse.swt.events.ShellAdapter#shellActivated(org.eclipse.swt.events.ShellEvent)
		 */
		public void shellActivated(ShellEvent e) {
			if (fMarkOccurrenceAnnotations && isActivePart()) {
				fForcedMarkOccurrencesSelection= getSelectionProvider().getSelection();
				SelectionListenerWithASTManager.getDefault().forceSelectionChange(JavaEditor.this, (ITextSelection)fForcedMarkOccurrencesSelection);
			}
		}