Create a widget for a desktop environment which is a one-line command line, with which one can launch GUI applications or even run sequences of commands all in one line e.g., separated by semicolons in bash syntax.
If clicked on, the widget can expand to display a full terminal window complete with any console output the GUI commands may have emitted. The widget probably runs a virtual terminal, e.g., screen or tmux, to be able to nicely redisplay output at any desired window size.
Typically GUI applications should be started and backgrounded, i.e., &. Provide a feature that backgrounds commands by default, so the widget remains available to accept more commands. Perhaps it backgrounds after a delay or user activity in the just opened GUI window. Maybe also some way of distinguishing console output of different backgrounded applications. Perhaps each application runs in a separate "screen" window, though that thwarts things like cd.
This should be easy.