public synchronized void clearUndoOnChange() {
		if (flattenModCount == -1) {
			flattenModCount = dbHandle.getModCount();
		}
	}
Flag the next transaction end to check for subsequent database modifications 
and clear undo/redo stack if changes are detected.  This call is ignored if 
there is already a pending check.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/compositeeditor/CompositeViewerDataTypeManager.java