Fl_Slider | +----Fl_Scrollbar
The Fl_Scrollbar widget displays a slider with arrow buttons at the ends of the scrollbar. Clicking on the arrows move up/left and down/right by linesize(). Scrollbars also accept FL_SHORTCUT events: the arrows move by linesize(), and vertical scrollbars take Page Up/Down (they move by the page size minus linesize()) and Home/End (they jump to the top or bottom).
Scrollbars have step(1) preset (they always return integers). If desired you can set the step() to non-integer values. You will then have to use casts to get at the floating-point versions of value() from Fl_Slider.
Creates a new Fl_Scrollbar widget using the given position, size, and label string. You need to do type(FL_HORIZONTAL) if you want a horizontal scrollbar.
Destroys the valuator.
This number controls how big the steps are that the arrow keys do. In addition page up/down move by the size last sent to value() minus one linesize(). The default is 16.
The first form returns the integer value of the scrollbar. You can get the floating point value with Fl_Slider::value(). The second form sets value(), range(), and slider_size() to make a variable-sized scrollbar. You should call this every time your window changes size, your data changes size, or your scroll position changes (even if in response to a callback from this scrollbar). All necessary calls to redraw() are done.