Mouse scroll fails when wrap_lines=True for Window

[Arrowbox]

I've not completely nailed down what the exact issue is. But when the buffer has many lines that are longer than the width and wrap then the mouse scroll sometimes gets stuck. Using keyboard to move the cursor beyond the edges does work but mouse scroll just doesn't respond.

[Arrowbox]

Okay, I've narrowed it down

@property
def content_height(self):
        """
        The full height of the user control.
        """
        return self.ui_content.line_count

When line wrap is on, the ui_content.line_count does not match the number of lines available to display. So in the scroll down function:

    def _scroll_down(self):
        " Scroll window down. "
        info = self.render_info

        if self.vertical_scroll < info.content_height - info.window_height:
            if info.cursor_position.y <= info.configured_scroll_offsets.top:
                self.content.move_cursor_down()

            self.vertical_scroll += 1

the self.vertical_scroll reaches the limit of the comparison before the actual end. I tried calculating the actual available height when the RenderInfo is initialized but that caused too much overhead.

I also removed the check before changing the scroll. The do_scroll function does adjust if we are out of bounds. It doesn't look like the performance takes a hit.