You are adding the stack to the window:
You are then constructing an object called grid that you're packing the StackSidebar into, but then the grid doesn't get added to the window.
So you probably need add (grid) instead.
You seem to be missing one last step, actually calling the function that is supposed to save the new values in the gsettings schema. To do this, you need to connect the delete_event signal to your before_destroy () function. I like to place that right before calling show_all ():
Also, the before_destroy () function must return false for the window to ...
install Elementary SDK (this fix may work if you run into errors in 5.1 hera):
sudo apt install elementary-sdk
install a compiler:
sudo apt-get install cmake
assuming you have git already set up, clone the repository you want to work on (eg. wingpanel-datetime-panel):
git clone https://github.com/elementary/wingpanel-indicator-datetime.git
change into ...