Begin(): fixed calling Begin() more than once per frame setting `window_just_activated_by_user` which in turn would set Appearing to true for that frame.
Begin(): fixed calling Begin() more than once per frame setting `window_just_activated_by_user` which in turn would set Appearing to true for that frame.

cmaughan/imgui,ggtucker/imgui,mikesart/imgui,elect86/imgui,Pagghiu/imgui,burningreggae/imgui,Flix01/imgui,Pagghiu/imgui,thevaber/imgui,bkaradzic/imgui,wflohry/imgui-addons,tom-seddon/imgui,dougbinks/imgui,aimotive/imgui-glfw,wflohry/imgui-addons,elect86/imgui,ocornut/imgui,cmaughan/imgui,Flix01/imgui,aimotive/imgui-glfw,mikesart/imgui,cmaughan/imgui,Flix01/imgui,ggtucker/imgui,bkaradzic/imgui,nProtect/imgui,ocornut/imgui,cmaughan/imgui,nProtect/imgui,tom-seddon/imgui,burningreggae/imgui,ocornut/imgui,bkaradzic/imgui,dougbinks/imgui,thevaber/imgui,ggtucker/imgui,nProtect/imgui