class Gun : public WithGunLayout<TopWindow> 
{
.....;
Withkep_lay <StaticRect> mj;  
.....;
}

Gun::Gun()
{
.....
CtrlLayout(mj);
summa_vievver.Add(mj.SizePos(),"Image"); // So mj will fill all suma_vievver available area when resizing
.....
}