Imgui: DirectX9 example becomes unresponsive when rendering interrupted by external activity

[KriyenKP]

Not sure how to word the issue title really...but hopefully my description explains it.

Basically what i found is that when the rendering is interrupted ImGui stops responding to user input but only on the graphical level. So if I cause a UAC dialog to popup from another application, or if I lock my pc and unlock it, this happens. The buttons no longer react to being hovered on and the dialogs all don't respond. I thought maybe I broke something but I did it on a clean build of the example project (the direct x 9 one ) and the same happens. The functions of the buttons however still respond. So I have a button to launch a url and the button fires when clicked, but the graphical ImGui changes don't. So no hover, pressed or state changes happen.

[ocornut]

Hello, I can confirm the issue, it seems to only happen with the DirectX9 demo and it's not really a problem in core imgui. I think we need to change the code in main.cpp to handle Lost Devices:
https://msdn.microsoft.com/en-us/library/windows/desktop/bb174714(v=vs.85).aspx

[ocornut]

Should be fixed with the code I committed in main.cpp

        // Handle loss of D3D9 device
        if (result == D3DERR_DEVICELOST && g_pd3dDevice->TestCooperativeLevel() == D3DERR_DEVICENOTRESET)
        {
            ImGui_ImplDX9_InvalidateDeviceObjects();
            g_pd3dDevice->Reset(&g_d3dpp);
            ImGui_ImplDX9_CreateDeviceObjects();
        }