Win32: Fix GLFW_MAXIMIZED ignored by first window

Fixes #780.

README.md

@@ -81,6 +81,8 @@ does not find Doxygen, the documentation will not be generated.
 ## Changelog
 
 - Bugfix: The range checks for `glfwSetCursorPos` used the wrong minimum
+- [Win32] Bugfix: The first shown window ignored the `GLFW_MAXIMIZED` hint
+                  when the process was provided a `STARTUPINFO`
 
 
 ## Contact

src/win32_init.c

@@ -319,6 +319,10 @@ static HWND createHelperWindow(void)
         return NULL;
     }
 
+    // HACK: The first call to ShowWindow is ignored if the parent process
+    //       passed along a STARTUPINFO, so clear that flag with a no-op call
+    ShowWindow(window, SW_HIDE);
+
     // Register for HID device notifications
     {
         DEV_BROADCAST_DEVICEINTERFACE_W dbi;