Reduce the size of a GtkScale indicator

[Bas Wassink <b wassink ziggo nl>]

Hey there,

I'm working on some code the uses a bunch of GtkScale's, but 
unfortunately the indicator (the thing you grab with the mouse) is way 
too large.

I'd rather not break the user's theme but still provide a smaller 
indicator to save vertical space. So how do I go about this? Are there 
CSS properties to set this, or do I provide my own image for the 
indicator (breaking the user's theme)?

I've looked at the Gtk3 docs and googled for setting the indicator size, 
but did not come up with a satisfying answer.

(I should probably also note this application is supposed to run on 
Linux, BSD, MacOS and Windows)

Any hints?

--Compyx