General observations on the Zoom user interface
The Zoom video meeting desktop application has different windows and types of controls. It regularly uses three main windows. These windows have overlays, drop down menus, and regular buttons.
Some buttons move around between different windows, based on the currently active features. For example, the mute / un-mute button moves around based on whether screen sharing is active on your machine.
Some labels look like buttons but are in fact not buttons.
There is a taskbar on the bottom of one of the main windows that contains buttons. Other buttons and labels can be found on the top edge, or above the bottom taskbar.
There is also one main windows that has a right-click menu.
There are other separate windows that pop up when clicking controls on the main windows, such as the chat window.
As a whole it is messy. Some of the user interface choices are perhaps understandable due to the functionality in the application.
The least user-friendly part of the application can be seen during fullscreen mode. When a participant shares a screen it is immediately shown fullscreen to the other people.
During some meetings the shared screen window has a menu that occurs when the mouse comes close to the top edge. It can be used to exit fullscreen.
Unfortunately there appears to be a different type of screen sharing as well. During other meetings the fullscreen shared window does not have any button to turn the fullscreen window in to a regular window. There are no controls at all. Moving the mouse or clicking the screen does not make any controls appear. The escape key does not work. In a sense, Zoom locks the user out of their computer. It turns out that double-clicking the video on the shared window exits the full-screen mode. The double-clicking is not obvious. It is the only double-clicking in the application.
It should be easy to escape fullscreen mode. Especially in the case of Zoom screen sharing. The user did not choose to enter fullscreen mode. Zoom did that by itself. This is confusing to the user.