I have finally found the cause of this (I think). This happens if "Reveal pointer" is switched on in Mouse and Touchpad system settings. It also affects inline renaming of bookmarks in Thunar (but no renaming files in that application because that is done with a dialog). I suspect it is therefore a bug in the GtkTreeView or GtkCellRendererText and not in Files. I'll see if I can find a work around.
I have finally found the cause of this (I think). This happens if "Reveal pointer" is switched on in Mouse and Touchpad system settings. It also affects inline renaming of bookmarks in Thunar (but no renaming files in that application because that is done with a dialog). I suspect it is therefore a bug in the GtkTreeView or GtkCellRendererText and not in Files. I'll see if I can find a work around.