I know that if someone wants to choose a color, he can promote QPushButton to KColorButton. Is there something similar when someone wants to open up a KDE file dialog?

If not, what's the best way to handle this? Create a QPushButton and call QFileDialog:: ?

In case it helps someone in the future KUrlRequester is the answer.

https://api.kde.org/frameworks/kio/html ... ester.html

In case you wanted a cross-platform API supporting multiple unix gui toolkits, I wrote a kdialog / zenity wrapper API for Linux which uses the native Win32 API on Windows and Cocoa on macOS with full support for all the latest Desktop operating systems, although it needs a few tweaks to get it working in OpenSolaris and the BSD's. Note that on OpenSolaris and BSD you would need to use the Linux source for compiling, and the Linux code at runtime will check if KWin is the current window manager and based on if that is true it will use kdialog for Qt dialogs otherwise it will use zenity for GTK+.

More info and downloads can be found here:
https://github.com/time-killer-games/DialogModule

I believe you can just simply include the "DialogModule.h" header in your Qt/KDE project and the functions should "just work".