Misc shallow merge to reduce diff in other branches.

backends/imgui_impl_dx10.cpp

@@ -47,7 +47,7 @@
 #pragma comment(lib, "d3dcompiler") // Automatically link with d3dcompiler.lib as we are using D3DCompile() below.
 #endif
 
-// DirectX data
+// DirectX10 data
 struct ImGui_ImplDX10_Data
 {
     ID3D10Device*               pd3dDevice;

backends/imgui_impl_opengl2.cpp

@@ -69,6 +69,16 @@
 #include <GL/gl.h>
 #endif
 
+// [Debugging]
+//#define IMGUI_IMPL_OPENGL_DEBUG
+#ifdef IMGUI_IMPL_OPENGL_DEBUG
+#include <stdio.h>
+#define GL_CALL(_CALL)      do { _CALL; GLenum gl_err = glGetError(); if (gl_err != 0) fprintf(stderr, "GL error 0x%x returned from '%s'.\n", gl_err, #_CALL); } while (0)  // Call with error check
+#else
+#define GL_CALL(_CALL)      _CALL   // Call without error check
+#endif
+
+// OpenGL data
 struct ImGui_ImplOpenGL2_Data
 {
     GLuint       FontTexture;
@@ -155,7 +165,7 @@ static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_wid
 
     // Setup viewport, orthographic projection matrix
     // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
-    glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
+    GL_CALL(glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height));
     glMatrixMode(GL_PROJECTION);
     glPushMatrix();
     glLoadIdentity();