In Thunderbird+, the shortcut control+backspace is assigned to close tabs and certain windows.
This causes a hotkey conflict when composing a message.

To restore the deletion of the word preceding the cursor in a message being written, this assignment must be deleted.

To do this, follow these steps:
* Place yourself in the main window of Thunderbird;
* Press NVDA+n to open NVDA menu;
* Press the letter: p, to place in the Preferences submenu;
* Then press the letter: N, to open the  Input gestures dialog;
* In the tree structure, select the branch: Thunderbird+ and open it with the right arrow;
* Press the letter: S, to select the branch: Send Control+F4 to the current window, and open it;
* Select lower branch: control+backspace;
* and finally, press Tab until you hear "Delete, button" then press Enter;
* It is important to close this dialog with the OK button to save your changes.

Noticed :
After these first manipulations, it may happen that it does not work as expected.
For some unknown reason, NVDA inserts the Control+Backspace gesture again.
In this case, repeat the procedure described above, this will solve this problem.