Improve windows IME status control

Author: halx99

src/win32_window.c

@@ -2883,17 +2883,40 @@ void _glfwSetIMEStatusWin32(_GLFWwindow* window, int active)
 {
     HWND hWnd = window->win32.handle;
     HIMC hIMC = ImmGetContext(hWnd);
-    ImmSetOpenStatus(hIMC, active ? TRUE : FALSE);
-    ImmReleaseContext(hWnd, hIMC);
+    if (active)
+    {
+        if (!hIMC)
+        {
+            hIMC = ImmCreateContext();
+            ImmAssociateContext(hWnd, hIMC);
+        }
+        if (!hIMC)
+        {
+            _glfwInputErrorWin32(GLFW_PLATFORM_ERROR, "ImmCreateContext failed");
+            return;
+        }
+		ImmSetOpenStatus(hIMC, TRUE);
+        ImmReleaseContext(hWnd, hIMC);
+    }
+    else if (hIMC)
+    {
+        ImmSetOpenStatus(hIMC, FALSE);
+        ImmReleaseContext(hWnd, hIMC);
+        ImmAssociateContext(hWnd, NULL);
+    }
 }
 
 int _glfwGetIMEStatusWin32(_GLFWwindow* window)
 {
     HWND hWnd = window->win32.handle;
     HIMC hIMC = ImmGetContext(hWnd);
-    BOOL result = ImmGetOpenStatus(hIMC);
-    ImmReleaseContext(hWnd, hIMC);
-    return result ? GLFW_TRUE : GLFW_FALSE;
+    if (hIMC)
+    {
+        BOOL result = ImmGetOpenStatus(hIMC);
+        ImmReleaseContext(hWnd, hIMC);
+        return result ? GLFW_TRUE : GLFW_FALSE;
+    }
+    return GLFW_FALSE;
 }
 
 EGLenum _glfwGetEGLPlatformWin32(EGLint** attribs)