From a strictly technical point of view, this is possible, although it requires a fairly large amount of code rewriting. The self-initializing function getExistingDirectory needs to be replaced with a custom QFileDialog, encapsulated in a new method, and manually designed to behave in the same way, so to select only directories. Then, the /Volumes/ path could be added in it by using setSidebarUrls.
But, we should not forget that this issue was actually created by the use of non-native QFileDialogs instead of native dialogs, and that we had to introduce it as a workaround for some obscure qt4 bug on macOS. In macOS native file dialogs, this issue does not exist because the Finder shows all the mounted volumes in its sidebar.
Fixing this issue will require writing a substantial amount of macOS specific code that
could stop working in the next major macOS release in a few days
violates Apple's Human Interface Guidelines as it exposes the /Volumes/ folder to the GUI
will become obsolete the day Syncplay migrates to qt5.
So, at this moment, I think this issue should not be fixed. I am of course open to suggestions.
@Et0h I tend to agree, although we are not providing anymore a guide to manually install Syncplay on macOS, so this possibility will be available only for experienced users. Maybe we should just leave this issue open until we switch to PySide2 in packaged .exe and .dmg .