Formerly INI keys were changed live when changing the value through a
panel, eliminating the need to loop through the panels for output.
However, this introduced more and more intermediate loops (like
disabling child panels of Dropdown, Choice, ... that are not shown) and
gave some headaches when working with missing mandatory values and
similar things. Hence, now we keep the original INI values read from
file as they are and and do loop through the elements at the end to get
the user set values.
Also add a few toolbar buttons and minor changes here and there.