This is a really handy shortcut that will quickly display the Tabs dialog box. It’s so simple that all you do is to double-click on your Ruler just below the markings appearing there. Make sure you double-click at the bottom of the ruler, not at the top. If you double-click at the top, the Page Setup dialog will appear.
Please note that when you double-click on your Ruler, you may also inadvertently set a tab stop. If you want to delete the newly placed tab stop, you can do so at the Tabs dialog or you can simply drag it off your Ruler.
You are welcome!