Keyboard and Proxmox. The problem seems to have multiple facets.
For instance, from a system using fr-ca keyboard, I can open the Proxmox web interface (IP address, port 8006), log in, create and run virtual machines, etc. But if I change my Proxmox password (using Proxmox's dialog that won't display what I type) and use a dead key combination to include a character with a diacritic, it will work fine within the password-defining dialog because, of course, I use the same sequence of keystrokes in both text boxes. But if I then log out and try to log back in, that same sequence of keystrokes fails miserably. Why is Proxmox apparently using two different keyboard drivers/adaptors/translations between the two dialogs? I mean, both dialogs are supplied by Proxmox and should therefore behave identically, no?