Press Shift-Esc at any time to show or hide the Doomsday UI.
The task bar contains (from left to right):
The first three items on the left comprise the console UI. You can use the console command prompt to enter console commands (see Console introduction).
The command menu [>] provides a way to define a shortcut key for opening and focusing the command prompt for quickly entering console commands. It can also be used to toggle the prompt between Quake-style console and Doomsday Script modes. This is mostly of use to advanced users and developers.
The console menu, in the left corner, has functions related to log messages. You can for example adjust how much detail gets printed to the log, whether warnings and errors should pop up an alert notification icon, and whether the log should contain developer-oriented messages.
Most of Doomsday's configuration settings are found in the ⚙️ menu.
The available selection of settings depends on whether a game is currently loaded. As a rule, settings that only appear when a game is loaded are specific to that family of games (e.g., to all versions/variants of Heretic). For example, “MIDI Sound Font” under “Audio” is a game family specific setting.
An exception to the above are the Renderer Appearance settings, which apply to all games.
Note that game-related settings, such as player control bindings and HUD display settings, are only available in the game's Options menu that is accessed via the game main menu.
The next page goes into more detail about the contents of the config menu.
In addition to the “Quit” and “Unload Game” functions, the application menu has some useful additional features as explained in the Readme.