Adding window visibility configuration flag.

src/core.c

@@ -2247,6 +2247,9 @@ static bool InitGraphicsDevice(int width, int height)
     //glfwWindowHint(GLFW_AUX_BUFFERS, 0);          // Number of auxiliar buffers
 
     // Check some Window creation flags
+    if (configFlags & FLAG_WINDOW_HIDDEN) glfwWindowHint(GLFW_VISIBLE, GL_FALSE);       // Visible window
+    else glfwWindowHint(GLFW_VISIBLE, GL_TRUE);     // Window initially hidden
+
     if (configFlags & FLAG_WINDOW_RESIZABLE) glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);       // Resizable window
     else glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);  // Avoid window being resizable
 

src/raylib.h

@@ -410,8 +410,9 @@ typedef enum {
     FLAG_WINDOW_RESIZABLE   = 4,    // Set to allow resizable window
     FLAG_WINDOW_UNDECORATED = 8,    // Set to disable window decoration (frame and buttons)
     FLAG_WINDOW_TRANSPARENT = 16,   // Set to allow transparent window
-    FLAG_MSAA_4X_HINT       = 32,   // Set to try enabling MSAA 4X
-    FLAG_VSYNC_HINT         = 64    // Set to try enabling V-Sync on GPU
+    FLAG_WINDOW_HIDDEN      = 32,   // Set to create the window initially hidden
+    FLAG_MSAA_4X_HINT       = 64,   // Set to try enabling MSAA 4X
+    FLAG_VSYNC_HINT         = 128   // Set to try enabling V-Sync on GPU
 } ConfigFlag;
 
 // Trace log type