Avoid forceRePaint() (and showing the full page without any
widget) between closing the "Looking up..." info message and
displaying the Dictionary result window, as it's not really
needed (I must have added it for symmetry with
ReaderDictionary:showLookupInfo() where it is needed.)
This avoids some occasional refresh competition glitches.
Also trim spaces at start or end of selection (can't hurt),
and replaced ugly string.gsub(text) with text:gsub().
b3efd5a333