Background
I'm building a PyQt5 application, that I'd like to have a dark theme for. Previously I've worked with Android development where there was a dark theme that I could set for an whole application
Question
Is there a dark theme built into Qt (that applies to all widgets in an application, and that is cross-platform)?
Founded in my bookmarks. I don't remember the original source.
P.S. it may be adjusted with QSS if necessary.
No, but you may use my fairly comprehensive stylesheets that should look excellent on most platforms (it's inspired by KDE's Breeze Theme, which is a dark theme that is quite elegant). This was (hard) forked from the excellent QDarkStylesheet, which I felt had theme issues in numerous areas, so I modified it extensively for my own needs and added a light theme.
Simple Use
A sample of the theme is here. To use it in PyQt5, simply add the following lines to a project:
Dynamic Stylesheet Toggling
In response to a comment, the easiest way to adjust the stylesheet to use either the light or the dark stylesheet dynamically is to wrap it in a function. You may then use the function as a slot to a Qt signal (warning: I primarily develop using C++, so there may be small errors in my code for the signal/slot mechanism).
Now we can add generic application logic that can use this function in a signal/slot mechanism (using a lambda as a convenient wrapper, if needed, to provide the path to the stylesheet toggler):
This allows users to dynamically change the theme of an application developed with PyQt5 (or using analogous logic in C++, Qt5) to either a light or dark theme.
Disclaimer: Obviously I am the maintainer.