Using an AZERTY keyboard, when trying to select all the text in let's say a chat message, you need to use CTRL+Q instead of the default CTRL+A. This might be because this function is hard coded to QWERTY keyboards where the "A" is on the same position as "Q" on AZERTY keyboards.
This has been in the game for a few versions (since 1.13) now and it's really annoying for someone with an AZERTY keyboard use to using the CTRL+A shortcut.