draw_list->AddRectFilled(ImVec2(x,y),ImVec2(x+thickness,y+sz),col32);x+=spacing+spacing;// Vertical line (faster than AddLine, but only handle integer thickness)
draw_list->AddRectFilled(ImVec2(x,y),ImVec2(x+1,y+1),col32);x+=sz;// Pixel (faster than AddLine)