I can confirm both problems, first, that the CKAN.dmg version doesn't work, and second, that extra drives aren't shown.

The CKAN.dmg sends me to the CKAN wiki page

@Maxzhao1999 You will need mono 5 and this file (Link removed, get https://github.com/KSP-CKAN/CKAN/releases/latest) to work

@rbcsky5, thanks, it's a big help to our investigations when we can firmly rule out user error. :)
My gut says this is a Mono bug (that file dialog is a standard one, not CKAN-owned), but I'll check whether there are extra flags we can pass to control the popup.

In the meantime, running ckan consoleui in a Terminal might work for you. You would have to type the full path to your KSP folder yourself (I think it would start with /Volumes ?), but it shouldn't be limited like the GUI apparently is.

Found someone else suffering from this, with no solution:

• https://stackoverflow.com/questions/34503898/monos-system-windows-forms-openfiledialog-wont-allow-me-to-access-usb-drive-i

I experimented with OpenFileDialog.CustomPlaces, but it seems to do nothing, even on Linux (where My Computer does contain all the drives). The rest of OpenFileDialog's properties don't seem to relate to controlling which drives show up.

LOL if it is a bug of mono, would you mind to open an issue there for us/me please? Since I have no idea what to do if they ask about codes.

Confirmed, Mono's FileDialog hard-codes a Linux-specific path /proc/mounts in its mounted device search, and it completely ignores any exceptions that may cause. This path doesn't exist on MacOSX from what I can tell, hence Mono not being able to find mounted devices on MacOSX:

https://github.com/mono/mono/blob/e456f910530906612291e0db09ac81d04e4b87ca/mcs/class/System.Windows.Forms/System.Windows.Forms/FileDialog.cs#L4736-L4740

I did a quick search for "FileDialog" in Mono's issues list and nothing came up, so this may not have been reported formally yet. I'm guessing they'd rather have a pull request for a fix, though, and I don't have a Mac with which to do the development. The only person I know doing any CKAN-related development on a Mac recently is @phardy, but I don't know whether he'd be interested in this kind of problem.

This is a duplicate of #1276, though the appearance of the window apparently has changed since then.
I'm going to close that one and keep this one, though, since this one has useful investigation info in it.

@HebaruSan According to this post: mono/mono#7791

it was fixed by this may be unstable file

https://download.mono-project.com/archive/nightly/macos-10-universal/MonoFramework-MDK-master@e610e443cd6-dirty-5.13.0.559.macos10.xamarin.universal.pkg

May be you guys wanna add this to to ckan page :)

Cool! Nice job getting this addressed, @rbcsky5!

I don't think we necessarily want to recommend nightly builds in general, in case they have other bugs that would cause problems for people, but it's good to have an option for folks who need to use external drives, and we can update the wiki once there's a new release of Mono with this fix.

No need to keep this issue open anymore; CKAN isn't going to do development on it, and Mono already did.