Size controls: relative and absolute

The options for selecting an arrow size in Visio never fail to make me chuckle:

The relative size descriptions are not very precise (though in Visio's defense they do provide a preview of the size once you select an option). It makes me want to see what might lay beyond Jumbo and Colossal... perhaps Ginormous?... or Humongous?

In this situation, it's probably clearer to show the arrow sizes rather than describe them. PowerPoint does this--though it's always struck me odd that it uses a variety of arrow types (rather than a single representative type or the arrow type you've selected.)

Showing relative sizes is one approach. The other approach is let users specify an exact (absolute) size--as with line width in PowerPoint (specified in points).

This approach has the advantage of giving users precise control over the size, but it may be hard to visualize the size you are selecting. (PowerPoint does dynamically change the line width on the page as you make selections in the dialog, but users may not notice this, particularly where the dialog is over the line you are editing.)

Visio provides some "pre-set" line sizes that are shown visually, with the option to set an absolute size via the More Line Weights... option.

MindManager provides no option to enter an absolute line width, but does provide the point size next to each line width option for reference: