SUMMARY KDE Plasma allows icon sizes to be set for the 'Toolbar', 'Main Toolbar', 'Small Icons', 'Panel' and 'Dialogs', provided that the icon theme's index.theme file provides the necessary information and icons in the requisite sizes are available. These settings have no effect, however, on the icons in - Application Menu (and the general list of entries in the Application Launcher); - System Tray; - System Settings, side bar. They also do not affect the icons in the Dolphin side bar which - unlike other parts of the interface - has its own icon size setting. The user will not, likely, encounter any usability issues if they scale their desktop using a global scale of 175% or more since at this scale all icons should be easy to identify. However, if they set KDE Plasma to use a 100% scale they can only set some parts of the interface to use larger icons: icons in the system tray, for instance, will become, and remain, tiny on a standard 4K monitor. This behaviour is highly inconsistent - especially if one takes into consideration that, in addition to the icons used in some parts of the interface, fonts, title bar buttons and window frames, too, can be set to use an appropriate size. STEPS TO REPRODUCE 1. Use a high-resolution monitor (e.g. 4K) 2. Set global scale to 100% 3. Attempt to resize icons by using the 'Configure icon sizes' menu. OBSERVED RESULT Inconsistent results: the size of icons used in some parts of the interface can be changed, while icons used in other parts of the interface cannot. EXPECTED RESULT The size of icons in all parts of the interface can be changed. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: 5.22.3 KDE Frameworks Version: 5.84.0 Qt Version: 5.15.3 ADDITIONAL INFORMATION
Indeed, these are ancient legacy settings which are mostly used for toolbars in older QWidgets apps and we are moving away from using them anywhere. Note that changing icon sizes is not a supported or recommended way to achieve global scaling. It is strongly encouraged to set the global scale to 200% rather than trying to make icons or text huge and hoping and praying that everything else scales up properly. The result is usually a visual mess.
Thank you for the reply; I appreciate it! This may not be the best place to ask, but does the global scale setting actually up - or downscale items (using something like e.g. the Lanczos algorithm), or does it cause the DE to use smaller or larger alternatives if those are available?
For apps that use Qt scaling, it scales the original thing up or down. I don't know whal algorithm is used. For Plasma when not using Qt scaling (i.e. on X11 unless you set the PLASMA_IUSE_QT_SCALING=1 environment variable), it will actually use the larger versions of the assets, if available.
Thank you!