Comment 10 for bug 1372781

*facepalm*

Quaoar,

first: the name of the configuration file is *config.ini* - why you tried edit *default_config.ini* (Hint: Stellarium User Guide - http://www.stellarium.org/wiki/index.php/Advanced_Use#The_Main_Configuration_File)

second: screen_w and screen_h sets the display dimensional when application in windowed mode (Hint: Stellarium User Guide - http://www.stellarium.org/wiki/index.php/Configuration_file#Section_.5Bvideo.5D)

third: Stellarium used Qt framework for the GUI and if you want scaling GUI you should set environment variable for Qt, e.g. QT_DEVICE_PIXEL_RATIO=2 is for Qt. Rules for set environment variable is very different for different operating systems and you should find it yourself. For example I use Linux and I know how it can be set on linux.

final: Qt 5.3 has initial support of 4K monitors. I guess Qt 5.4 and, better, Qt 5.5 has more good support of 4K monitors. Apparently you need build Stellarium from source code with Qt 5.4.1 or Qt 5.5.

Members of Stellarium development team doesn't has any 4K monitors and we can't check support of those monitors.