c++ - MFC create Modeless dialog that does not lose focus -

i want create dialog in mfc that, once shows up, can't lose focus. blocking user access main sdi window, while processing data. flow similar to:

1. user triggers process
2. application shows dialog
3. application starts process function

i can't modal dialog, because domodal() function doesn't return until dialog closes, never trigger step 3.

how can done?

edit

these functions notifying task start , task end:

void cmodguiapp::_notify_task_start() {   _processing_dialog->domodal(); }  void cmodguiapp::_notify_task_end() {   _processing_dialog->enddialog(1); } 

this code triggering task process:

void trigger_task(std::function<void()> f) {   cmodguiapp::_notify_task_start();   f();   cmodguiapp::_notify_task_end(); } 

try following approach:

1. call

   _processing_dialog->domodal();

2. on process dialog class wherever appropriate:

   afxgetapp()->getmainwnd()->sendmessage(wm_your_user_message)

3. on main window class message map, add

   on_message(wm_your_user_message, yourusermessagehandlerfunction)

4. implement yourusermessagehandlerfunction(). have retaken handling @ main window.