Return a textbox widget object. The win argument should be a
curses WindowObject in which the textbox is to be contained.
The edit cursor of the textbox is initially located at the upper left
hand corner of the containin window, with coordinates (0, 0).
The instance's stripspaces flag is initially on.
This is the entry point you will normally use. It accepts editing
keystrokes until one of the termination keystrokes is entered. If
validator is supplied, it must be a function. It will be called
for each keystroke entered with the keystroke as a parameter; command
dispatch is done on the result. This method returns the window
contents as a string; whether blanks in the window are included is
affected by the stripspaces member.
This data member is a flag which controls the interpretation of blanks in
the window. When it is on, trailing blanks on each line are ignored;
any cursor motion that would land the cursor on a trailing blank goes
to the end of that line instead, and trailing blanks are stripped when
the window contents is gathered.