To_Do

--hight priority
-->use load_properties in all widgets
simplify value_text_box
remove border for text background
use pango layout instead of cairo text functionnalities
clean calendar 
create a grid widget
clean helpers (some methods with too much parameters)
try to be consistent with the use of h_margin/v_margin names or h_padding/v_padding

--average priority
add more options in volume.lua (choose card, mpd address, mpd password ...)

Check all values in superproperties and in all files some of them doesn't match so user cannot modify some parameters:
check all for tagslist values
create a border value for tagslist (user set it with a color and a border of 1 px is displayed)
add superproperties values for task_warrior
Check in all files the usage of local values that have been set using user_value or superproperties value or nil