The programmable completion feature in FluidShell permits typing a partial command, then pressing the [Tab] key to auto-complete the command sequence. For example

:$ expo[TAB Key] << Will complete to 'export'

If auto-complete fails due to availability of multiple (command) completion paths then pressing [Tab] key again will display a pop-up window containing all possible options. Please refer to the image below for an example of this

Auto-completion also works for command arguments and Shell variables. As can be seen from the next image

Another example

:$ echo $LIN[TAB Key] << will complete to $LINENO