ZN wrote: 
> One should also make a difference between flicker and what is called
> 'frame shear'.

Yes, I used "flicker" as a generic word for all king of weird effects.

> It may be possible (but is probably unduly complex) for QPC to
> implement tripple buffering,

Wouldn't even help much as QPC doesn't know when to switch the
buffers. The application would need a way to signal when it's finished
with drawing.

> While at the subject of the PE - I was always under the impression that:
> 1) the PE saves the image of the application window, not a background (i.e.
> what is under the window), except where saving what is under the menu
> panes.

Yes, the PE saves the contents of a window once it gets covered by
another window, i.e. a window that is always in the foreground never
gets saved. But open a 1x1 window over it and the whole thing is
copied into RAM.

> 2) there was a mechanism that alowed jobs to provid for their own window
> maintaining regardless of the background save mechanism

As far as I know this mechanism is pretty much "hard coded" into the
whole PE, i.e. all the routines rely on valid save areas.

> I was also under the impression that programs using old QL modes under GD2
> still save their windows internally as old QL mode bitmap, but the restore
> included conversion on the fly (I thought this plus changes in screen
> driver to handle cases where direct writing to screen RAM applied, were how
> the palette extensions of GD2 were implemented).

No, there are no "QL mode" applications under GD2. The old calls are
just translated into the higher colour depth but all applications are
allowed to make use of the new calls, too, i.e. a complete high colour
copy is always needed.

Marcel

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