We recently upgraded to Version 188.8.131.52 as part of re-installing UltraVNC onto a new Windows 10 notebook.
In my first session with a client (using Single-Click), I discovered that the file transfer icon was no longer present in the toolbar at the top of the viewer window. I assumed that Windows 10 had some security 'improvement' that blocked UltraVNC's file transfer facility, and it was therefore not offered in the toolbar. I have since upgraded to Version 184.108.40.206, and this is still the case. So for the last month or so, I have had to resort to other mechanisms to transfer files to and from various clients.
However, yesterday my colleague somehow accidentally right-clicked in the viewer's title bar during a remote session, and was offered a popup menu that contained the File Transfer facility. I get the same on my Windows 10 notebook. (Great!!!)
However, a hidden menu like that is not at all intuitive !!! I wonder how many other users have upgraded to recent versions and been stymied by this same change to the UI.
Please add the File Transfer icon back into the Tool Bar ASAP.