Basically: whenever you resize the main window, the power columns in the right-hand pane are also resized.
However in the most recent version of Mids (1.91) I've noticed that this resizing is bugged in that a thick "black vertical bar" appears to the right of the power columns, this bar increases in width as you shrink the window size.
This black bar eats into the visible screen area for displaying the power bars and can make viewing builds in small window sizes unbearable.
This is particularly noticeable at smaller sizes. At a system resolutions of 1024x768, with the window at Maximum the bar extends to roughly the "P" in the "Pop-Up: Off" button. At lower window sizes, it can extend much further. At greater sizes, the bar can disappear completely (the power bars stop being actively resized at roughly ~1100 pixels window width on my screen - at this point a vertical scroll bar appears).
See screenshots for
Small Size,
Medium Size and
Large Size examples.
