Overclocking. I still don't understand it. To the extent that I will not even try to install HD 720p video recording because it requires overclocking.
Swap. I don't know what it is. At all.
And I would like to know how to compile Fortran or Ada on-device. I can compile C or C++, thanks to gcc and g++, though I don't use it much.
Qt-GTK theming. It seems to me that any Qt application attempting to theme itself like a native application uses hard-coded paths to theme images, instead of somehow reading gtkrc file of the theme.
Maybe, there is something else. I don't remember at this moment.
Best wishes.
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Per aspera ad astra...