▁head ▁and ▁foot ▁of ▁each ▁door ▁to ▁be ▁secured ▁in ▁one ▁movement . ▁The ▁sl ender ▁window ▁join ery ▁maxim izes ▁light ▁into ▁the ▁room ▁and ▁minim izes ▁the ▁visual ▁impact ▁of ▁the ▁door way ▁join ery ▁when ▁considered ▁extern ally . ▁The ▁doors ▁of ▁a ▁French ▁window ▁often ▁open ▁out ward ▁onto ▁a ▁bal con y , ▁por ch , ▁or ▁terra ce ▁and ▁they ▁may ▁provide ▁an ▁entrance ▁to ▁a ▁garden . ▁ ▁A ▁l ouv red ▁door ▁has ▁fixed ▁or ▁mov able ▁wooden ▁fins ▁( o ften ▁called ▁sl ats ▁or ▁l ou vers ) ▁which ▁permit ▁open ▁vent ilation ▁while ▁pres erving ▁priv acy ▁and ▁prevent ing ▁the ▁passage ▁of ▁light ▁to ▁the ▁interior . ▁Being ▁relatively ▁weak ▁structures , ▁they ▁are ▁most ▁commonly ▁used ▁for ▁w ard ro bes ▁and ▁dry ing ▁rooms , ▁where ▁security ▁is ▁of ▁less ▁importance ▁than ▁good ▁vent ilation , ▁although ▁a ▁very ▁similar ▁structure ▁is ▁commonly ▁used ▁to ▁form ▁window ▁shut ters . ▁Double ▁l ouv red ▁doors ▁were ▁introduced ▁into ▁Se ag ate , ▁built ▁in ▁Florida ▁in ▁ 1 9 2 9 ▁by ▁G wend ol yn ▁and ▁Pow el ▁C ros ley , ▁that ▁provided ▁the ▁desired ▁circul ation ▁of ▁air ▁with ▁an ▁added ▁degree ▁of ▁priv acy ▁in ▁that ▁it ▁is ▁impossible ▁to ▁see ▁through ▁the ▁fins ▁in ▁any ▁direction . ▁ ▁A ▁composite ▁door ▁is ▁a ▁single ▁leaf ▁door ▁that ▁can ▁be ▁solid ▁or ▁with ▁glass , ▁and ▁is ▁usually ▁filled ▁with ▁high ▁density ▁fo am .