MacDraw does not support a true tab function.
When the tab key is pressed in MacDraw, a representation of the character
is displayed. For example, the Courier tab character has a width, whereas
the Helvetica tab character does not -- so Courier moves the insertion
point over the width of the tab character.
This is not really the tab function that is written into many other
applications, which inserts a defined amount of space when a tab (ASCII
code 9, horizontal tab) is received. With a tab function, it's not the
character width being displayed, but the code being interpreted by the
application, which inserts the defined amount of space.
There is no correlation between a space or tabs in MacDraw. The tab
differs, different depending on the font selected and whether the tab
character has been given a character width.