Fixed #2210 by adding a workaround for failure of event.isPopupTrigger()

To avoid reigniting #2103, this is only activated on Windows. This basically just sees manually if the button was number 3.
I have tested a case the user has set "Switch primary and secondary buttons" in Control Panel > Mouse: works OK.

Also fixed #2180 tab characters not drawn/recognized in the editor, by adjusting the drawing code to reflect that tabs don't have width 1 character in all cases.