grdTransparent apply settings to groups. Then, you could have popup2 and label in the same group. By modifying transparency to that group, both popup2 and label will be affected... Since it's like that, I guess you can't apply different transparency level to individual label.
But, let's say "There could be tricky ways":
Leave grdTransparent and put the stuff you want to be transparent in a lsbox and use the lsboxtransparency setting.