Bottom bar not draggable

According to the docs I should be able to drag a window using the bottom bar. However that does not always work as advertised. 

I always disable auto recalculation of the border thickness, and set the it explicitly in code. However, depending on some ordering and timing issues (apparently) I can or cannot drag the window using the bottom bar. I can't exactly say under what conditions it works or doesn't work. But in one instance, I have a window where it works when I prepare the bottom bar in -windowDidLoad, but it doesn't work when I prepare the bottom bar in an action method (using the exact same code). It also sometimes may or may not work depending on whether I change the border thickness before or after I resize the main view for my content area. 

One thing that's clear is that it's an AppKit bug, rdar://problem/7358898.

So my question is whether there is some method I can send to the window to have it notice that it its draggable area has changed, or some other workaround to make sure the dragging always works? Clearly, -setContentBorderThickness:forEdge: does not properly do this.

Thanks,
Christiaan