Ok, after several days I figured it out. Now my only question is -- does anyone know how to make the child window fade in and out?
WinGet, active_id, ID, A
Gui, BlackScreen: New, +Parent%active_id% +HwndBlackScreenId1, BlackScreen
TempVar := A_ScreenHeight +100
Gui, BlackScreen: Show, h%TempVar% w%A_ScreenWidth%
Gui, BlackScreen: Color,Black,000000
WinSet, Top, , ahk_id %BlackScreenID1%
OnMessage(0x0022, "BlackScreenActivate") ; WM_BlackScreenACTIVATE
BlackScreenActivate() {
If (A_Gui <> "BigBox") && (A_Gui <> "BlackScreen1") {
Gui, BlackScreen1:+LastFound
WinSet, Top
}
}