Button
Icons

		Collapse into previous class selector
		Expand collapsed class selector
		Show/Hide filter controls and optional columns
		Minimize / Restore
		Union mode / Intersection mode
		Hide filter control

For those controls which might toggle between two states, a "mouse rollover" is shown on the right side. Note that toggling a button image makes sense only when the displayed image corresponds to the state assumed after the button is pressed rather than to the current active state. Therefore, it may not make sense for the Union / Intersection buttons -- i.e. those should probably be displayed as two distinct bi-stable buttons with "radio button" (exclusive) behavior. [Phil 1-4-05].