In[]:=
src=
NoPlcAssLnge1.1
[[1]];​​rt2=Keys@src;​​iz1={200,19};​​pip12="Variables";​​pip22="Creating";​​pip32="Set";​​styl={14,FontWeight"Medium",FontFamily->"Source Code Pro"};​​​​Dynamic@Column[{​​Dynamic@PopupMenu[Dynamic@pip12,rt2,rt2[[1]]​​,ImageSize->iz1​​,ContentPadding->False​​,Appearance->"Frameless"​​,BaseStylestyl​​,MenuStylestyl],​​Row[{Spacer@16,Dynamic@PopupMenu[Dynamic@pip22,Keys@src[pip12],(Keys@src[pip12])[[1]]​​,ImageSize->iz1​​,ContentPadding->False​​,Appearance->"Frameless"​​,BaseStylestyl​​,MenuStylestyl]}],​​Row[{Spacer@32,Dynamic@PopupMenu[Dynamic@pip32,src[pip12][pip22],(src[pip1][pip2])[[1]]​​,ImageSize->iz1​​,ContentPadding->False​​,Appearance->"Frameless"​​,BaseStylestyl​​,MenuStylestyl]}]​​,​​Dynamic@Column@{pip32,{pip12,pip22,pip32}}​​},Spacings0,AlignmentLeft]
Out[]=
PopupMenu[
pip12
,rt2,rt2〚1〛,ImageSizeiz1,ContentPaddingFalse,AppearanceFrameless,BaseStylestyl,
MenuStylestyl]
PopupMenu[
pip22
,Keys[src[pip12]],src[pip12],ImageSizeiz1,ContentPaddingFalse,AppearanceFrameless,
BaseStylestyl,MenuStylestyl]
PopupMenu[
pip32
,src[pip12][pip22],pip2,ImageSizeiz1,ContentPaddingFalse,AppearanceFrameless,
BaseStylestyl,MenuStylestyl]
pip32
{pip12,pip22,pip32}