Launch on specific screen

General
1

If I work out what screen an app is running in at the time it closes, how can I ensure that it launches on the same screen next time?
(Customer with two screens complains that my apps always open on screen (0) )

2

On Windows I would save the top & left values to the registry & read them back on next launch checking that those positions were available now (in case the external monitor had been removed).

3

Save window position:

call ParentWindow.NSWindowMBS.saveFrameUsingName(WindowTitle)

Load window position:

call ParentWindow.NSWindowMBS.setFrameUsingName(WindowTitle)

Doing the calculations for loading the window position is a major PITA.

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4

Interesting that it uses title. I like the idea, but NS functions aren’t cross platform sadly (I realise I didnt say it needed to be)

Top and Left - didnt realise that these continued over two screens - I had the feeling that x,y co-ordinates also needed a screen number to make sense - like 20,40 could exist on two differnt screens.

5

You can use Wayne’s approach on Windows and the MBS call on macOS.

6

Just be aware that you’ll run into positioning issues (when only using “top” and “left”) on TargetWindows if the 2 (or 3) monitors have different Scale Factors.
Long story with this Xojo Issues (multi monitor, multi scale factors)…

That’s why I’m using this: jo-tools/monitors: Xojo example project: Monitors (github.com)

Note the right hand side of the example (which is using Windows API):

  • Labels: “IsOnMonitor” and “at relative Monitor Pos”
    • to read the Window position (e.g. before closing)
  • Button "Position on Screen [num] at Pos (x, y) → button [Pos] (on the right hand side, using Windows API)
    • to restore the previously saved position when opening the window
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