`set_title` would call `update_buffer` at the end of the function, even
if the bar was explicitly not supposed to be drawn (most commonly
because the window had been fullscreened). Since `set_title` is called
outside of the decorations file, a check here made the most sense.
Resolves#310.
The `title_pixmap` function assumed if `title` was not empty, the returned
`glyphs` from `layout_title_glyphs` would also not be empty.
`layout_title_glyphs`, however, could break before a single insertion if
`max_width` was too small. Emacs, when using `emacsclient
--create-frame`, could call `title_pixmap` with a `max_width` of 1,
causing a panic. Closes#311.
These simple decorations will be rendered only when the host compositor doesn't
support server side decorations and the X11 window does not render its own
decorations.
Closes#31
