Since version 17 we've introduced Tab Leaders, allowing you to fill the spaces in tabs with a character. For example, in a table of contents:
To set a tab character, you must first create a custom tab stop. Let's create one from scratch now.
Create a blank new document (File > New)
Press Ctrl + L to show the rulers (or Window > Bars > Rulers)
Select the text tool (T), and draw a text area
Now, within the top of the page on the ruler, click on the bar to create a custom tab stop at that location. The icon at the left denotes the alignment. You can click it to change what sort of tab stop to create (you can change this later).
|Left Align: The text will be aligned to the left side of the tab stop
|Right Align: The text will be aligned to the right side of the tab stop
|Center Align: The text will be centered to the tab stop
|Decimal Point: The decimal points will be aligned to the tab stop
After creating the tab stop, right-click on it > Tab stop properties.
Here, you will see this properties dialog
Simply enter the leader character in the field, and click OK.
Enter some text, for example, 'Water' and press Tab. The cursor will now move over to the tab stop and the space in-between will filled with the character you have just set. You could do a few things here like enter a price and design a menu.
If you insert a table of contents (Insert > Table of Contents), this will automatically insert a period as a tab leader. Similar to the above, you can select the Text tool, click within and update the character if you wish.
Import and Export
Please note that many formats don't support all characters as tab leaders, and may be replaced or omitted when you import it into another application. If you want maximum compatibility, it's recommend to use either periods or hyphens.