OpenWindowedScreen() and alpha transparency

[Mindphazer]

It seems there's a problem with alpha tranparency in a OpenWindowedScreen on MacOS.
The sample code below displays 20 squares with increasing alpha transparency.
It works fine on Windows
But on MacOS (MacBook pro M4, MacOS 26.2, PB 6.21), all squares are white, no transparency is applied.

Code: Select all

InitSprite()
OpenWindow(0, 0, 0, 330, 160, "", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
OpenWindowedScreen(WindowID(0), 0, 0, DesktopScaledX(330), DesktopScaledY(160))

Repeat
  Repeat
    Event = WindowEvent()
    If event = #PB_Event_CloseWindow
      End 
    EndIf
  Until Event = 0
  If StartDrawing(ScreenOutput())
    DrawingMode(#PB_2DDrawing_AlphaBlend)
    For i = 1 To 20
      Box(DesktopScaledX(i * 15), DesktopScaledY(50), DesktopScaledX(14), DesktopScaledY(14), RGBA(255, 255, 255, 255 - (i * 10)))
    Next i
    StopDrawing()
  EndIf
  FlipBuffers() 
  ClearScreen(0)
ForEver

Can anybody else confirm ?