Comment 142 for bug 193141

Created an attachment (id=300873)
enable left pane as a drop target

this is for testing only, as already pointed in comment #23 candrop is checking if root is a readonly folder, that should not happen since even if root is readonly, its children could be writable!
So this removes that check, then we should ensure that getdroppoint makes a good job in don't allowing putting items into wrong places (it should really be updated to take in count excludeitems).
Dropping into items should work now that we have the new folderItemId used in insertionPoint.

NOTICE that applying this patch will expose a full number of new bugs in drag & drop (like dropping in the empty area below tree, dragging tags, dragging queries, dragging roots, dragging in all Bookmarks and so on), but without this finding them will be even more difficult.

this is for drag inside left pane, and to/from left pane, does not solve any bug in the right pane flatlist.