Changing integer with variable that holds an integer doesn't work

You need to use a concatenation for your variable to work.  Since TabToUpdate is a variable, you can't just embed it in a string, you need to indicate that it is a variable containing a string.



so, change your line of code to the following:

Aliases["DesktopMainWindow"]["Source_MainWindow"]["MainWindow"]["LayoutRoot"]["NavigationDockPanel"]["NavigationPane"]["ContentPane"]["TOCTree"]["LayoutRoot"]["NavigationalPaneTOCTree"]["ClickItem"]("|[" + TabToUpdate + "]");