Lock width of window

[bueke]

I'm currently using a size command to set the window width of foobar2000 to 20%. Unfortunately this setting doesn't persist if you resize other windows or if you move it to another workspace. Or if you have three columns open but close one of them, then foobar will expand to fill 50% of the screen, when what I want is for foobar to stay at 20% while the other remaining column expands to fill the remaining 80%. Is there any way to achieve this?