test itk_component

 itk_component add min_res_e {
 SettingEntry $itk_component(toolbar).minre low_resolution_limit \
     -image ::img::min_res16x16 \
     -type real \
     -precision 2 \
     -width 5 \
     -justify right \
     -balloonhelp "Low resolution limit"
    }

==========================

 SettingEntry .c low_resolution_limit \
     -image ::img::min_res16x16 \
     -type real \
     -precision 2 \
     -width 5 \
     -justify right \
     -balloonhelp "Low resolution limit"

pack .c