Now that Xojo supports macOS Mojave Dark mode with the release of Xojo 2018r3, it is very easy to get an app supporting Dark mode.
However if your app uses HTMLViewers in some areas, the background will remain white when switching to Dark mode.
There is an easy fix for this using Dark_HTMLViewer now available on Github: https://github.com/jkleroy/Xojo-Dark-HTMLViewer
I can’t get this to work in my project. I copied the Dark_HtmlViewer to my main project. Changed the super of my HtmlViewer to Dark_HtmlViewer. Then I added
if IsDarkMode then
HTMLViewer1.ChangeAppearanceToDark
end if
in the Open event of the HtmlViewer (just for testing). When I run my app I see only white on white. A bit later I see some text but black on white and not vice versa. My html is loaded with a thread/timer combo because it’s email data from a database.