void selectProgram2() {
		if (primaryProgram != null) {
			String msg = primaryProgram.getDomainFile().getName() +
				" already has a Diff view. Only one is allowed at a time.";
			tool.setStatusInfo(msg, true);
			Msg.showWarn(this, diffListingPanel, "Diff Already In Progress", msg);
			return;
		}

		selectAndOpenProgram2();

		actionManager.setOpenCloseActionSelected(secondaryDiffProgram != null);
		getDiffDetailsProvider();
	}
Computes the differences between program1 and program2 that are displayed in the browser. It
allows the user to specify the Diff settings to use.
Ghidra/Features/ProgramDiff/src/main/java/ghidra/app/plugin/core/diff/ProgramDiffPlugin.java