Bug 216811 [Markers] ExtendedMarkersView#setFocus doesn't
The result is that focus is lost if you drag the view to another stack... The most common implementation seems to be 'viewer.getControl().setFocus()... To test: select an element in the Problems or Tasks view. Drag the view to a new location (could be in an existing stack or a new one) notice that while the view is the active view the arrow keys don't navigate...
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/ExtendedMarkersView.java
private void setPrimarySortField(MarkerField field, TreeColumn column) {
		builder.setPrimarySortField(field);
		IWorkbenchSiteProgressService service = (IWorkbenchSiteProgressService) getViewSite()
				.getAdapter(IWorkbenchSiteProgressService.class);
		builder.refreshContents(service);
		updateDirectionIndicator(column, field);
		viewer.refresh();
		reexpandCategories(builder);
	}
	/**
	 * Add group to the enabled filters.
	 * 
	 * @param group
	 */
	void toggleFilter(MarkerFieldFilterGroup group) {
		builder.toggleFilter(group);
	}
	/**
	 * Toggle the sort direction of the primary field
	 */
	void toggleSortDirection() {
		setPrimarySortField(builder.getPrimarySortField());
	}
	/**
	 * Update the direction indicator as column is now the primary column.
	 * 
	 * @param column
	 * @field {@link MarkerField}
	 */
	void updateDirectionIndicator(TreeColumn column, MarkerField field) {