Failing to draw on a Gtk.DrawingArea - gtk

Question

I'm not able to draw, i've already read tutorials, i can't find the problem.
I simply have a correct UI drawed by Glade. Then i want to draw, for example 50 drawing areas. So i create a Grid with 50 cells; for each cell there is a vertical box (with a drawing area and a label inside each one). But i can't seen anything drawed.
class collega_GUI:
def __init__(self):
try:
self.__builder = Gtk.Builder()
self.__builder.add_from_file('UI2.glade')
self.__Grid = Gtk.Grid()
self.__Grid.set_margin_left(20)
self.__Grid.set_margin_right(20)
self.__Grid.set_row_spacing(10)
self.__Grid.set_column_spacing(15)
self.__Grid.set_column_homogeneous(True)
self.__GridBox = self.__builder.get_object('box11')
self.__GridBox.pack_end(self.__Grid, 1, 1, 20)
indirizzi_ip = []
for i in range(50):
indirizzi_ip.append(str(i))
cpu_info = {}
for ip in indirizzi_ip:
cpu_info[ip] = dict()
left = 0
right = 0
for ip in indirizzi_ip:
cpu_info[ip]['drawing_area'] = Gtk.DrawingArea()
cpu_info[ip]['drawing_area'].set_size_request(100, 100)
cpu_info[ip]['drawing_area'].set_name(ip)
box = Gtk.VBox(False, 5)
box.add(cpu_info[ip]['drawing_area'])
label = Gtk.Label(ip)
box.add(label)
self.__Grid.attach(box, left, right, 1, 1) #object,left,right,top,bottom
cpu_info[ip]['drawing_area'].connect("draw", self.__draw)
label.show()
cpu_info[ip]['drawing_area'].show() #the draw should start now!
box.show()
# 5 drawing areas in a row
left += 1
if left == 5:
right += 1
left = 0
self.__builder.get_object('Azioni_Window').show()
Gtk.main()
except Exception as xe:
logging.error('%s' % str(xe))
sys.exit()
def __draw(self, widget, context):
context.set_source_rgb(0.9, 0, 0.1) #rosso
context.set_source_rgb(0.1, 0.9, 0) #verde
context.set_source_rgb(0.8, 0.7, 0) #giallo
context.set_source_rgb(0.8, 0.7, 0.8) #inattivo
context.rectangle(0, 0, widget.get_allocated_width(), widget.get_allocated_height())
context.fill()
if __name__=='__main__':
try:
UINX=collega_GUI()
except Exception:
sys.exit()

Answer 1

You're missing
self.__Grid.show()
And hence nothing in the grid is shown.
In general it's easier to just call show_all() on some top-level container rather than trying to remember to show() every individual widget.