fixed border size around axes

Hello,

Searching on the MPL-users and -devel for set_position did not produce
any leads on this topic, so I doubt it's possible but ...

When using MPL as a widget within an application, I find it hard to set
the relative position of the axes in such a way that is appropriate
over a wide range of total window sizes.

That is, I've assigned set_position so that the tick and axis labels
don't get clipped when the widget it small (while trying to maximize the
area that displays the plot). But then the widget gets enlarged , it
seems like there is a lot of wasted space in the border -- space that I
wish were usable for the plot itself.

So I ask: Is there any way to set the border size in pixels instead of a
percentage of the total widget size?

Thank you!
Glen Mabey