void secondProgramClosed() {
		openCloseDiffViewAction.setSelected(false);
		openCloseDiffViewAction.setDescription("Open Diff View");
		showDiffSettingsAction.setEnabled(false);
		diffDetailsAction.setEnabled(false);
		removeActions();
	}
Notification to the action manager that the second program to the
program Diff was closed. Actions are adjusted accordingly.
Ghidra/Features/ProgramDiff/src/main/java/ghidra/app/plugin/core/diff/DiffActionManager.java