[Larix] Remove support for system dark mode and enforce light theme only?

[maurov]

@newville I open here a separate thread on the "dark mode support" issue. Hoping more constructive than #548.

Unless someone else wants to take care of it, my personal solution would be supporting only light theme for Larix and other Larch GUIs, even if the system mode is dark. Do you agree with this? If yes, how we could force the Wx widgets to ignore the system dark mode and stay in a light theme?

It is true that the current situation under Linux and Windows makes working with Larix very difficult if the system is in dark mode.

[newville]

@maurov Much of the Dark/Light mode is done at the "System Library Level". wxPython can report that Dark Mode is set or not, but I don't think there is a way to force one mode or the other. The trouble is that wxWidgets (library) and wxPython (wrapper) don't have 100% coverage for all derived widget classes, and we use some of those. We can have some colors react and be set properly, but if colors are hardwired into widgets, they have to react to the Mode. It's a work in progress.

My understanding is that this is supposed to "get better" on the wxWidgets/wxPython side, but that might take a bit of time for that.

[maurov]

@newville OK, I understand better now. Let's wait then for a better dark mode support on the Wx side. I propose to keep this issue open as a reminder.

[maurov]

@newville I have seen that you have worked on improving the dark mode in the last commits. Have you considered simply to force always light mode, independently of the system settings?

[newville]

@maurov I did consider that. For a while now (year+? This issue is from June), wxPython automatically respond to dark mode, changing default colors based on that mode. The options are either to force all colors (foreground and background) for every widget, or to adapt.

I sort of knew "adapt" was needed, but would not be fun. But also, I think that this "support dark and light mode decently" is mostly done for Larix.

The 'wxutils' project has some derived widgets and code shared in Larix and my beamline/epics GUIs too. That library now has dark/light mode colors and allows for "callback events" when the color mode changes, using the 'darkdetect' library. Larix + other GUIs can mostly "just use the updated wxutils" derived widgets anddo much less setting of colors themselves. They can also register a callback to run when that mode changes, mostly to re-color the small number of explicitly colored widgets.

This is mostly done and working well, or at least "ready for feedback and bug reports". I have done no testing on Linux - I basically never run Linux as a desktop, and I'm not 100% sure how well KDE vs GTK vs Wayland would actually handle any of these changes anyway.

I'll need to push out an update of wxmplot (also adapted to wxutils) first -- maybe later today.

A minor release of Larix with these updated dependencies might come later this week, or perhaps early next. I don't really have too many other changes, at least not for Larix.

[maurov]

@newville thanks for the update on this topic and all the work done. I do not have a strong opinion on this. It is great if wxutils can handle color mode. My point here is that, independently of the system color mode, one may want to set light or dark mode. IMHO, Larix in dark mode under Linux is currently a nightmare and I would like to have the possibility to force light mode even if my system is set to dark.

[newville]

@maurov if you are up for testing it on Linux, I would be happy to hear reports with using the updated wxutils (2026.1.0) and wxmplot. This should do a much better job for the Group List, for the Notebook tabs, and for most of the "Tables". And, yes, these were basically useless. I don't see any remaining cases of "dark text on dark background", but there may be one or two lurking somewhere...

I am less confident about automatically adapting to changes in Color Mode. This works reasonably well on Mac and Linux - there are a few oddities in outlines of some buttons and other widgets, but none of these are a disaster.

[maurov]

@newville sorry for not giving a feedback so far, very busy on the beamline these days. Yes, I will test soon the updated version on Linux.

[newville]

@maurov Thanks -- I have not yet tried this on a linux desktop that supports dark mode either. But, I am also willing to say that we can just declare victory (especially after a few fixes, including #610), and tag and release 2026.1.2 that has much better support for dark mode, at least on Mac and Windows.