Tooltip for a drawable object?

Im creating a series of boxes via draw_rectangle and wanted to attach a
tooltip to any given box, is there a way to do this? Example of my
draw_rectangle code:

x = boxlocations[axis_y_value][axis_x_value].x
y = boxlocations[axis_y_value][axis_x_value].y
w = boxlocations[axis_y_value][axis_x_value].width
h = boxlocations[axis_y_value][axis_x_value].height

gc =,w,h,-1))
gc.fill = Gdk::GC::Fill::SOLID
gc.rgb_fg_color = Gdk::Color.parse(color)

a = area.window.draw_rectangle(gc, true, x, y, w, h)