Slate: Keeping an SWindow on top

I’m spawning an SWindow separate from the game viewport, however, when I click in the viewport, the SWindow is sent to the back. How can I keep it on top? Alternatively, any way to spawn SWindows inside the viewport?

Currently I am deriving from SWindow, and in Tick am calling BringToFront(), but that feels a bit kludgy and I don’t know if it will affect other widgets such as tooltips and such. Also, when I click in the viewport, there is a definite flickering.