Bug 5677 Hierarchy outline has empty space
I opened a hierarchy view on IActionDelegate. Selected a few of the subinterfaces, changed the expansion state of the tree. Then, no matter which item I selected in the top window (the hierarchy tree), the bottom window (the outline table) always had exactly four empty rows before the first item was listed.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/dialogfields/ListDialogField.java
protected Button createButton(Composite parent, String label, SelectionListener listener) {
		Button button= new Button(parent, SWT.PUSH);
		button.setText(label);
		button.addSelectionListener(listener);
		MGridData gd= new MGridData();
		gd.horizontalAlignment= gd.FILL;
		gd.grabExcessHorizontalSpace= true;
		gd.verticalAlignment= gd.BEGINNING;
		gd.heightHint = SWTUtil.getButtonHeigthHint(button);
		gd.widthHint = SWTUtil.getButtonWidthHint(button);
	
		button.setLayoutData(gd);
		return button;
	}
	
	private Label createSeparator(Composite parent) {
		Label separator= new Label(parent, SWT.NONE);
		separator.setVisible(false);
		MGridData gd= new MGridData();
		gd.horizontalAlignment= gd.FILL;
		gd.verticalAlignment= gd.BEGINNING;
		gd.heightHint= 4;
		separator.setLayoutData(gd);
		return separator;
	}			
	/**
	 * Returns the composite containing the buttons. When called the first time, the control
	 * will be created.
	 * @param The parent composite when called the first time, or <code>null</code>