Open a sub-frame within any folder or the protocol or files frame of
a task window and return its id frame_id. The sub-frame must be
closed with the command CloseSubFrame. The main purpose of a sub-frame
is to group together consecutive lines which have the same variable visibility
status. Controlling their visibility collectively gives a smoother update
of the window.
-appearancecommand_string
The command string is any of the permissible options to the Tk command
frame which will be applied to the sub-frame.
The visibility status of the sub-frame is dependent on the value of
the parameter controlVar. If controlVar has any of the values
in the list default_values, the sub-frame will have the state
given by default_state which can be either open (the subframe
is visible) or hide (the subframe is not visible). It will have
the alternative state if the value of controlVar is not in the list
default_values.