In the desktop application, being able to control click or shift click multiple chats or multiple messages to perform the same action on each selected item, such as delete, forward, or copy. This functionality already exists in the mobile app (Android, at least).
Actual behavior
Only one chat or one message can be acted on at a time in the desktop application, which can be laborious and inefficient.
I think the easiest way would be to select the chats/messages via context menu or by holding down CTRL/CMD and left clicking.
A multiselector would make the use of DC-Desktop more comfortable.
In addition, the number of sync emails between devices would be reduced.
This is particularly important for users with cheap email providers.