Examples: GLFW: rework examples main loop to handle minimization without burning CPU or GPU by running unthrottled code. (#7844)

Backends: GLFW: added ImGui_ImplGlfw_Sleep() helper.

examples/example_glfw_opengl3/main.cpp

@@ -127,6 +127,11 @@ int main(int, char**)
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
         glfwPollEvents();
+        if (glfwGetWindowAttrib(window, GLFW_ICONIFIED) != 0)
+        {
+            ImGui_ImplGlfw_Sleep(10);
+            continue;
+        }
 
         // Start the Dear ImGui frame
         ImGui_ImplOpenGL3_NewFrame();