GtkSourceView - space drawing

Update: done in Tepl.

There is the SpaceDrawer class. What is missing is a simple SpaceDrawerChooser widget, to put e.g. in the preferences dialog of an application.

The SpaceDrawerChooser should contain by composition a SpaceDrawer object to store the properties.

The SpaceDrawerChooser should not provide a setting for non-breaking spaces, it should configure its SpaceDrawer to always draw non-breaking spaces, everywhere. I think that's a good default.

What would the widget look like:

• ☑ Draw spaces in selected text (once this feature is implemented).

• Leading spaces
  • ☑ Draw tabs
  • ☑ Draw spaces
• Spaces inside text
  • ☑ Draw tabs
  • ☑ Draw spaces
• Trailing spaces
  • ☑ Draw tabs
  • ☑ Draw spaces
  • ☑ Draw newlines