Fixed handling of window resize by imgui on UWP
Fixed handling of window resize by imgui on UWP

DiligentGraphics/DiligentSamples,DiligentGraphics/DiligentSamples,DiligentGraphics/DiligentSamples,DiligentGraphics/DiligentSamples,DiligentGraphics/DiligentSamples,DiligentGraphics/DiligentSamples