Bug 281126 [CSS] Illegal state exc from tab-height
If you just type a space in the CSS Editors SWT example you will get traces in the console failing on CSSValue.getFloatValue() for tab-height.
tests/org.eclipse.e4.ui.tests.css.swt/src/org/eclipse/e4/ui/tests/css/swt/CTabFolderTest.java
static public CSSEngine engine;
	
	protected CTabFolder createTestCTabFolder(String styleSheet) {
		Display display = Display.getDefault();
		engine = createEngine(styleSheet, display);
		
		Shell shell = new Shell(display, SWT.SHELL_TRIM);
		FillLayout layout = new FillLayout();
		shell.setLayout(layout);
		Composite panel = new Composite(shell, SWT.NONE);
		panel.setLayout(new FillLayout());
		CTabFolder folderToTest = new CTabFolder(panel, SWT.NONE);
		CTabItem tab1 = new CTabItem(folderToTest, SWT.NONE);
		tab1.setText("A TAB ITEM");
		
		engine.applyStyles(shell, true);
		shell.pack();
		return folderToTest;
	}
	
	protected Shell createShell(String styleSheet) {
		Display display = Display.getDefault();
		engine = createEngine(styleSheet, display);
		
		Shell shell = new Shell(display, SWT.NONE);
		
		engine.applyStyles(shell, true);
		shell.pack();
		return shell;
	}