1.8.5/1.8.6: Highlighting breaks with mixed Windows display scales

[ferdinand-fichtner]

I'm using Pympress 1.8.6 on a Microsoft Surface tablet running Windows 11. The tablet has a native resolution of 2880×1920, with display scaling set to 200%. It's connected via USB-C to an external screen or projector scaled at 100%. The presenter view runs on the tablet, and the presentation window is fullscreen on the external display.

Unfortunately, recent versions of Pympress don’t handle this mixed scaling setup well. Minor issues include:

• Font size mismatch (the title bar font in the presenter window is tiny, while other text is normal)
• Menus appear in incorrect positions (e.g. clicking “Presentation” opens the menu in a different location, possibly on the external screen)

The main issue is with highlighting:
Drawing in the presenter window initially works as expected, with highlights appearing correctly on both displays. However, as soon as I lift the stylus or release the mouse button, the highlights in the presenter window jump to a different location—apparently scaled incorrectly (coordinates seem to be doubled), causing a shift and enlargement toward the bottom right. The external display remains unaffected, but this makes writing or drawing connected elements unusable.

This only occurs with mixed scaling. The issue disappears if both displays use the same scaling (100% or 200%), but that’s not practical for regular use.

The problem was introduced in version 1.8.5. Version 1.8.4 works perfectly. Deleting pympress.ini does not resolve the issue.

Excerpt from pympress.log:

INFO:pympress.app:Pympress: 1.8.6 ; Python: 3.12.10 ; OS: Windows 11 10.0.26100 ; Gtk 3.24.49 ; GLib 2.84.1 ; Poppler 25.04.0 cairo ; Cairo 1.18.4 , pycairo 1.28.0
INFO:pympress.extras:Medienunterstützung: GdkPixbuf GIF-Player, GStreamer not available, VLC 3.0.20 Vetinari
WARNING:pympress.ui:Gtk.Application.inhibit konnte Bildschirmschoner nicht verhindern, probiere hartes Deaktivieren

Please let me know if I can help with testing or debugging. I really appreciate the new features since 1.8.4—looking forward to a fix whenever you have time.

Best regards,
Ferdinand

[Cimbali]

Thanks for reporting. I’m not sure that we handle scaling per-window, I’ll have to look at what we actually do currently.

[Cimbali]

So you’re saying running v1.8.4 doesn’t have the issue, right?

[ferdinand-fichtner]

yes, that's right. 1.8.4. wörks as expected.