I usually create a base window and inherits all my forms from that base, in the create method of the base form I place a loop:
Code:
uses TypInfo;
for i := 0 to ComponentCount -1 do
begin
if GetPropInfo(Components[i], 'Transparent') <> nil then
SetPropValue(Components[i], true);
end;
of course you can also put a if ClassType statement on top.
basically, in the base form I change all properties the way I want them to be, thus I don't need to change it manually in the property editor by hand.