StyledEdit scrolling bug when not using wrap lines option

[psycho_killer]

When wrap lines is disabled in StyledEdit the horizontal scroll bar behaves strangely / doesn't work. How to reproduce: Start StyledEdit and enable wrap lines. Copy this text (or any long paragraph) into StyledEdit and turn off wrap lines. Pay attention to the width of the window.

Experienced behaviour: The horizontal scroll bar does not give indication that the text continues to the right and the arrows do not work when clicked either. Resizing the window to expand to the right does not change anything about the scroll bar. But when resizing back to the left to make the window smaller than the initial width of the window the scroll bar / arrow is activated, BUT only up to the position of the initial width. Now re-enable wrap lines, resize window to a different width, disable wrap lines again. The new width is now the maximum width the scroll bar will recognize.

Excpected behaviour: Horizontal scroll bar works like the vertical one: Gives indication of the length of text to the right by its size, clicking on the empty part of the scroll bar result in a page right movement, clicking on the arrows work, etc.

Of course, trying to write with wrap lines off is useless as you can't see what you write. It should obviously be auto-scrolling to the right as you're writing. I should mention that the horizontal scroll works as expected in StyledEdit in R5, but only to an extent. After not too long you are doing invisible writing here too.

[jackburton]

dup of #4393