Make window buttons progress bars themeable

Registered by lokster

It would be good if the progress bars are made themeable/customizable in some way.
For example, making the x,y,w,h, and ro variables in make_progress_bar() customizable from the settings or the theme.
Possible values: absolute, in pixels or relative - in percent of the button width or height.
I think this is very easy to implement, and this way for example, the Win7 style can be mimicked fairly easy.

Working implementation can be found here: lp:~skss/+junk/dockbarx-progressbars

Blueprint information

Status:
Started
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None
Priority:
Undefined
Drafter:
None
Direction:
Needs approval
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Definition:
New
Series goal:
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Implementation:
Needs Code Review
Milestone target:
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Started by
lokster

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