This is a new issue (not the 'delete wrong file problem' you already fixed--thanks--but mentioned with it)
You cannot click and immediately drag a file in Pcmanfm ( detailed view & single-click to open). You have to hover 1/2 second before the file is actually selected. This allows you to select multiple file without the shift key, but I would say that 80% of the time, people are involved in selecting&dragging single files and would much prefer being able to click&drag immediately and use the shift key for multiple file selection. I used Rox-Filer for a while. It allows you to click&drag immediately, and so does Windows if I am correct. They work fine without the 1/2 second delay. Can the delay be removed?