AutoHotkey Community

OnMessage(0x14, "WM_ERASEBKGND")

splash = 28
SetTimer Animate, 50
Gui +ToolWindow
Gui add, pic, h100 w100, %splash%.gif
Gui Show,,Lunar Phase

Animate:
   GuiControl,,Static1, % "*w100 *h100 " (splash := mod(splash,28)+1) ".gif"
   WinSetTitle Lunar Phase,,Lunar Phase - %splash%
   GuiControl,,Static1, *w100 *h100 %splash%.gif
Return

WM_ERASEBKGND(wParam) {
    if (A_Gui = 1) {
        Gui, +LastFound
        hwnd := WinExist()
       
        GuiControlGet, pic, Pos, Static1
        ; these are sometimes 0 when the background is erased!
        ; (it seems to be erased while the picture is changing)
        picW := 100
        picH := 100
       
        hdc := DllCall("GetDC", "uint", hwnd)
       
        ; Exclude the picture control from the clipping region.
        DllCall("ExcludeClipRect", "uint", hdc
            , "int", picX, "int", picY, "int", picX+picW, "int", picY+picH)
       
        ; Draw a black rectangle over the whole GUI.
        VarSetCapacity(rect, 16)
        DllCall("GetClientRect", "uint", hwnd, "uint", &rect)
        DllCall("FillRect", "uint", hdc
            , "uint", &rect
            , "uint", DllCall("GetStockObject", "int", 0x4))
       
        DllCall("ReleaseDC", "uint", hwnd, "uint", hdc)
        return 1
    }
}

GuiClose:
ExitApp

OnMessage(0x14, "WM_ERASEBKGND")

splash = 28
SetTimer Animate, 50
Gui +ToolWindow
Gui add, pic, h100 w100, %splash%.gif
Gui Show,,Lunar Phase

Animate:
   WinSetTitle Lunar Phase,,% "Lunar Phase - " (splash := mod(splash,28)+1)
   GuiControl,,Static1, *w100 *h100 %splash%.gif
Return

WM_ERASEBKGND() {
   return 0
}

GuiClose:
ExitApp

; OK:
WM_ERASEBKGND(wParam) {
    return 0
}

; FAIL:
WM_ERASEBKGND(wParam) {
    g := A_Gui
    return 0
}

WM_ERASEBKGND(wParam) {
    wtf := A_AhkPath
    return 0
}

WM_ERASEBKGND(wParam) {
    ErrorLevel := "C:\Windows\explorer.exe"
    ErrorLevel := ErrorLevel
}