Not 100% sure on this, but you might not be using the latest mIRC version.

When I right click the switchbar, I can click on the following:

Background
Position
Lock Bars
Options...

On your toolbar, click on the last button (the yellow button) alternatively //echo -a $version also returns your version.

If you only have one window open (your status window) the whole switchbar will be filled with just the status window.

If you have 2 windows open one half of the switchbar will be the status window, the half will be another window.

Image 1 and Image 2