some Thunderbird popups can't be moved
Some popups, such as File->New->Folder, displays a popup that is fixed to the main window. If it blocks some useful information in the main window, the popup cannot be moved or resized. Trying to resize it moves the entire Thunderbird window. Some popups work independently, such as Edit->Preferences.
Thunderbird 52.5.0 (64-bit), Ubuntu 17.10 x86-64
Wšykne wótegrona (8)
File|New is a menu, is it not? Menus don't move.
Edit|Preferences (Tools|Options to Windows users) leads to a dialogue in a standalone window, so yes that can be moved.
That all seems absolutely normal to me.
File|New is a menu. File|New|Folder brings up a dialogue box, which, I thought, used to be movable.
File|New|Folder brings up a "New Folder" dialogue in a floating window here. (Windows 10).
I don't recall what happens on my Linux system. I'll check.
Wót Zenos změnjony
Another problem is when composing a message. If you insert an image, you get a file-select popup. If you try to move the popup, the message window moves instead of the popup!
And, as I said in my original message, this is happening in Ubuntu 17.10 x86-64
Is that gnome, KDE or something else?
Xorg, which, I think, includes gnome.
Using MX Linux with the Mate DE here and I can't reproduce either of these situations. The eventual dialogue window here is completely movable.
It happens when spell-checking before sending a message from the compose window.
Ubuntu Linux 17.10 x64 Thunderbird 52.8.0 Gnome window manager. Addon Messaging Menu and Unity Launcher integration can be enabled or disabled with the same result-can't move some popup windows, like the ones that spellcheck opens and puts ON TOP of the word that it thinks is spelled incorrectly. If I try to move the popup, the entire composition window moves.