I am trying to recreate some of the behaviors that occur when the combobox dropdown is open. When this happens, if there is a scrollviewer then scrolling gets ignored. The ability to resize the window is disable. I know that there is a ResizeMode, but the results of changing the mode are visibly jarring to the window. If the window goes from CanResize to NoResize, the minimize and restore down buttons are removed from the title bar, and the window seems to grow. I've tried to use reflector to disassemble the combobox to find where this behavior is created and I can't seem to track it down. I am needing to recreate this behavior for the same reason that I would guess that the combobox does. The use of a popup window. If content in the window gets moved while the popup is open. the popup stays in a fixed position. I'm hoping that somebody has an idea as to how this behavior is achieved.