Renders a spin button in a cell
<gtk-cell-renderer-spin> renders text in a cell like
<gtk-cell-renderer-text> from which it is derived. But while
<gtk-cell-renderer-text> offers a simple entry to edit the text,
<gtk-cell-renderer-spin> offers a <gtk-spin-button> widget. Of
course, that means that the text has to be parseable as a floating point number.
The range of the spinbutton is taken from the adjustment property of the cell
renderer, which can be set explicitly or mapped to a column in the tree model,
like all properties of cell renders. <gtk-cell-renderer-spin> also has
properties for the climb rate and the number of digits to display. Other
<gtk-spin-button> properties can be set in a handler for the
start-editing signal.
The <gtk-cell-renderer-spin> cell renderer was added in GTK+ 2.10.