void applyDiffAndGoNext() {
		applyDiff();
		NextDiffCommand nextCmd = new NextDiffCommand(this);
		tool.executeBackgroundCommand(nextCmd, primaryProgram);
	}
Callback when user changes selection in the program2 diff panel.

Note: A P2 selection is handed to this method when a selection is made in the diff listing
which displays P2.
Ghidra/Features/ProgramDiff/src/main/java/ghidra/app/plugin/core/diff/ProgramDiffPlugin.java