I am not sure if this is a new problem with 1.7.0.350 (RC1), because I didn't notice it until I had both of my PCs to that release. But here's what I'm seeing in .350:
Start with Photo maximized, and open some images. I tried it with 6.
Window > Float All and take note of the order/position of the floating windows.
Minimize Photo.
First issue: the screen sort of flickers as each individual floating window is minimized, and then Photo itself minimizes.
Now maximize Photo
Second issue: the floating windows are in a different order/arrangement than before Photo was minimized.
Minimize Photo again. (Issue from #4 repeats.)
Maximize Photo again. (Issue from #6 repeats.)
Interestingly, though, there seem to be only 2 different arrangements of the floating windows. Continuing to minimize/maximize Photo gives only these two different arrangements.