Bug 202316 [Forms] Add gradient sharing support for FormHeading
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/internal/forms/widgets/FormHeading.java
tbsize = toolbarCache.computeSize(SWT.DEFAULT, SWT.DEFAULT);
			}
			if (headClient != null) {
				clientCache.setControl(headClient);
				int cwhint = width;
				if (cwhint != SWT.DEFAULT) {
					cwhint -= HMARGIN * 2;
					if (tbsize != null && getToolBarAlignment() == SWT.BOTTOM)
						cwhint -= tbsize.x + SPACING;
				}
				clsize = clientCache.computeSize(cwhint, SWT.DEFAULT);
			}
			int totalFlexWidth = width;
			int flexWidth = totalFlexWidth;
			if (totalFlexWidth != SWT.DEFAULT) {
				totalFlexWidth -= TITLE_HMARGIN * 2;
				
				if (hasToolBar() && getToolBarAlignment() == SWT.TOP
						|| hasMessageRegion())
					totalFlexWidth -= SPACING;
				
				if (hasToolBar() && getToolBarAlignment() == SWT.TOP)
					totalFlexWidth -= tbsize.x + SPACING;
				flexWidth = totalFlexWidth;
				if (hasMessageRegion()) {
					
					flexWidth -= SPACING;
					
				}
			}