show zom/lat/lon/bearing in window title

common/glfw_view.cpp

@@ -1,5 +1,7 @@
 #include "glfw_view.hpp"
 
+#include <mbgl/util/string.hpp>
+
 GLFWView::GLFWView(bool fullscreen) : fullscreen(fullscreen) {
 #ifdef NVIDIA
     glDiscardFramebufferEXT = (PFNGLDISCARDFRAMEBUFFEREXTPROC)glfwGetProcAddress("glDiscardFramebufferEXT");
@@ -192,6 +194,12 @@ void GLFWView::make_active() {
 
 void GLFWView::swap() {
     glfwPostEmptyEvent();
+
+    double lon, lat, zoom;
+    map->getLonLatZoom(lon, lat, zoom);
+    const double bearing = map->getBearing();
+    const std::string title = mbgl::util::sprintf<128>("Mapbox GL – %.2f/%.6f/%.6f/%.1f", zoom, lat, lon, bearing);
+    glfwSetWindowTitle(window, title.c_str());
 }
 
 void GLFWView::notify_map_change(mbgl::MapChange change, mbgl::timestamp delay) {