winex11.drv: Ensure that the WGL context is removed from the context list in wglDeleteContext.

dlls/gdi32/opengl.c

@@ -135,11 +135,18 @@ BOOL WINAPI wglDeleteContext(HGLRC hglrc)
 
     TRACE("hglrc: (%p)\n", hglrc);
     if(ctx == NULL)
+    {
+        SetLastError(ERROR_INVALID_HANDLE);
         return FALSE;
+    }
 
     /* Retrieve the HDC associated with the context to access the display driver */
     dc = get_dc_ptr(ctx->hdc);
-    if (!dc) return FALSE;
+    if (!dc)
+    {
+        SetLastError(ERROR_INVALID_HANDLE);
+        return FALSE;
+    }
 
     if (!dc->funcs->pwglDeleteContext) FIXME(" :stub\n");
     else ret = dc->funcs->pwglDeleteContext(hglrc);

dlls/opengl32/tests/opengl.c

@@ -609,6 +609,11 @@ static void test_deletecontext(HDC hdc)
     HANDLE thread_handle;
     DWORD res, tid;
 
+    SetLastError(0xdeadbeef);
+    res = wglDeleteContext(NULL);
+    ok(res == FALSE, "wglDeleteContext succeeded\n");
+    ok(GetLastError() == ERROR_INVALID_HANDLE, "Expected last error to be ERROR_INVALID_HANDLE, got %u\n", GetLastError());
+
     if(!hglrc)
     {
         skip("wglCreateContext failed!\n");
@@ -639,6 +644,12 @@ static void test_deletecontext(HDC hdc)
     res = wglDeleteContext(hglrc);
     ok(res == TRUE, "wglDeleteContext failed\n");
 
+    /* Attempting to delete the same context twice should fail. */
+    SetLastError(0xdeadbeef);
+    res = wglDeleteContext(hglrc);
+    ok(res == FALSE, "wglDeleteContext succeeded\n");
+    ok(GetLastError() == ERROR_INVALID_HANDLE, "Expected last error to be ERROR_INVALID_HANDLE, got %u\n", GetLastError());
+
     /* WGL makes a context not current when deleting it. This differs from GLX behavior where
      * deletion takes place when the thread becomes not current. */
     hglrc = wglGetCurrentContext();

dlls/winex11.drv/opengl.c

@@ -1807,6 +1807,7 @@ BOOL CDECL X11DRV_wglDeleteContext(HGLRC hglrc)
         wine_tsx11_unlock();
     }
 
+    free_context(ctx);
     return TRUE;
 }