GTK: Fix potential IME input focus bug.

Do not wait idle to set the IME context focus, just set it right after the focus event process finished to fix potential IME input focus miss.

Author: 徐扬斌

src/gtk/window.cpp

@@ -4755,13 +4755,7 @@ bool wxWindowGTK::GTKHandleFocusIn()
     if (m_imContext)
     {
         // delay gtk_im_context_focus_in to avoid timing conflict with IME framework(fcitx)
-        g_idle_add([](gpointer data) -> gboolean {
-            GtkIMContext* context = static_cast<GtkIMContext*>(data);
-            if (context) {
-                gtk_im_context_focus_in(context);
-            }
-            return G_SOURCE_REMOVE; // only run once
-        }, m_imContext);
+        gtk_im_context_focus_in(m_imContext);
     }
 
     return retval;