Recalculate horizontal scrollbar width

[minesworld]

On start the scollbar is set to a width of 2000 . This will show the horizontal scrollbar even on empty editors.

The horizontal scollbar max value gets adjusted when the text will exceed this value. But it won't readjust to lower values when the max lines width is shortened.

The correct behaviour would be to set the max scrollbar value depending on the actual max line length.

[minesworld]

The easiest is the first step - set the default width to 1 instead of 2000. But: its gets complicated after that as there seem to be many codepaths when the scrollbar gets updated. But it is somehow "unclear" when which internal values will be calculated so that the real width of the horizontal scrollbar can be set...

Like some function to set the scrollbar are called more than once during a single update (like on keypress). Maybe it makes sense to update the scrollbars only via the timer callback?