Undecorated window support on win/mac/linux.

include/GL/glfw3.h

@@ -482,6 +482,7 @@ extern "C" {
 #define GLFW_ICONIFIED              0x00020002
 #define GLFW_RESIZABLE              0x00022007
 #define GLFW_VISIBLE                0x00022008
+#define GLFW_UNDECORATED            0x00022009
 
 #define GLFW_CONTEXT_REVISION       0x00020004
 #define GLFW_RED_BITS               0x00021000

src/cocoa_window.m

@@ -636,6 +636,14 @@ static GLboolean initializeAppKit(void)
     return GL_TRUE;
 }
 
+@interface GLFWWindow : NSWindow {}
+@end
+@implementation GLFWWindow
+- (BOOL)canBecomeKeyWindow {
+    return YES; // Required for NSBorderlessWindowMask windows.
+}
+@end
+
 // Create the Cocoa window
 //
 static GLboolean createWindow(_GLFWwindow* window,
@@ -643,7 +651,7 @@ static GLboolean createWindow(_GLFWwindow* window,
 {
     unsigned int styleMask = 0;
 
-    if (wndconfig->monitor)
+    if (wndconfig->monitor || wndconfig->undecorated)
         styleMask = NSBorderlessWindowMask;
     else
     {
@@ -654,7 +662,7 @@ static GLboolean createWindow(_GLFWwindow* window,
             styleMask |= NSResizableWindowMask;
     }
 
-    window->ns.object = [[NSWindow alloc]
+    window->ns.object = [[GLFWWindow alloc]
         initWithContentRect:NSMakeRect(0, 0, wndconfig->width, wndconfig->height)
                   styleMask:styleMask
                     backing:NSBackingStoreBuffered

src/internal.h

@@ -145,6 +145,7 @@ struct _GLFWhints
     int         auxBuffers;
     GLboolean   stereo;
     GLboolean   resizable;
+    GLboolean   undecorated;
     GLboolean   visible;
     int         samples;
     GLboolean   sRGB;
@@ -170,6 +171,7 @@ struct _GLFWwndconfig
     int           height;
     const char*   title;
     GLboolean     resizable;
+    GLboolean     undecorated;
     GLboolean     visible;
     int           clientAPI;
     int           glMajor;
@@ -216,6 +218,7 @@ struct _GLFWwindow
     // Window settings and state
     GLboolean           iconified;
     GLboolean           resizable;
+	 GLboolean           undecorated;
     GLboolean           visible;
     GLboolean           closed;
     void*               userPointer;

src/win32_window.c

@@ -739,6 +739,11 @@ static int createWindow(_GLFWwindow* window,
             window->win32.dwExStyle |= WS_EX_WINDOWEDGE;
         }
 
+        if (wndconfig->undecorated) {
+           window->win32.dwStyle = WS_POPUP;
+           window->win32.dwExStyle = 0;
+        }
+
         xpos = CW_USEDEFAULT;
         ypos = CW_USEDEFAULT;
 

src/window.c

@@ -176,6 +176,7 @@ GLFWAPI GLFWwindow* glfwCreateWindow(int width, int height,
     wndconfig.height        = height;
     wndconfig.title         = title;
     wndconfig.resizable     = _glfw.hints.resizable ? GL_TRUE : GL_FALSE;
+	 wndconfig.undecorated   = _glfw.hints.undecorated ? GL_TRUE : GL_FALSE;
     wndconfig.visible       = _glfw.hints.visible ? GL_TRUE : GL_FALSE;
     wndconfig.clientAPI     = _glfw.hints.clientAPI;
     wndconfig.glMajor       = _glfw.hints.glMajor;
@@ -215,6 +216,7 @@ GLFWAPI GLFWwindow* glfwCreateWindow(int width, int height,
 
     window->monitor     = wndconfig.monitor;
     window->resizable   = wndconfig.resizable;
+	 window->undecorated = wndconfig.undecorated;
     window->cursorMode  = GLFW_CURSOR_NORMAL;
 
     // Save the currently current context so it can be restored later
@@ -278,6 +280,7 @@ void glfwDefaultWindowHints(void)
 
     // The default is to show the window and allow window resizing
     _glfw.hints.resizable = GL_TRUE;
+    _glfw.hints.undecorated = GL_FALSE;
     _glfw.hints.visible   = GL_TRUE;
 
     // The default is 24 bits of color, 24 bits of depth and 8 bits of stencil
@@ -333,6 +336,9 @@ GLFWAPI void glfwWindowHint(int target, int hint)
         case GLFW_RESIZABLE:
             _glfw.hints.resizable = hint;
             break;
+        case GLFW_UNDECORATED:
+            _glfw.hints.undecorated = hint;
+            break;
         case GLFW_VISIBLE:
             _glfw.hints.visible = hint;
             break;
@@ -540,6 +546,8 @@ GLFWAPI int glfwGetWindowParam(GLFWwindow* handle, int param)
             return window->iconified;
         case GLFW_RESIZABLE:
             return window->resizable;
+        case GLFW_UNDECORATED:
+            return window->undecorated;
         case GLFW_VISIBLE:
             return window->visible;
         case GLFW_CLIENT_API:

src/x11_window.c

@@ -46,6 +46,16 @@
 #define Button6            6
 #define Button7            7
 
+typedef struct
+{
+	unsigned long flags;
+	unsigned long functions;
+	unsigned long decorations;
+	long input_mode;
+	unsigned long status;
+} MotifWmHints;
+
+#define MWM_HINTS_DECORATIONS (1L << 1)
 
 // Translates an X Window key to internal coding
 //
@@ -129,6 +139,17 @@ static GLboolean createWindow(_GLFWwindow* window,
             _glfwInputError(GLFW_PLATFORM_ERROR, "X11: Failed to create window");
             return GL_FALSE;
         }
+
+        if (wndconfig->undecorated) {
+            Atom motif_hints_atom = XInternAtom(_glfw.x11.display, "_MOTIF_WM_HINTS", False);
+            MotifWmHints motif_hints;
+            motif_hints.flags = MWM_HINTS_DECORATIONS;
+            motif_hints.decorations = 0;
+            XChangeProperty(_glfw.x11.display, window->x11.handle,
+                motif_hints_atom, motif_hints_atom, 32,
+                PropModeReplace,
+                (unsigned char *)&motif_hints, sizeof(MotifWmHints) / sizeof(long));
+        }
     }
 
     if (window->monitor && !_glfw.x11.hasEWMH)