qt.labs.platform.FileDialog hangs for 10-20 seconds

Steps to reproduce:

1 Click on main window -> file dialog will be opened in folder

StandardPaths.writableLocation(StandardPaths.PicturesLocation)

2 Chose any file in network location on other machine(for example network_machine)

3 Disconnect network_machine from net

3 Click on main window to open file dialog again

Expected result: 

File dialog will be opened at once

Actual result:

Application hangs and file dialog will be opened during 10 - 20 seconds

NOTE:
Debug showed that dialog hangs in openPanel time in qtbase/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm

method :
initWithAcceptMode:(const QString &)selectFile options:(SharedPointerFileDialogOptions)options helper:(QCocoaFileDialogHelper *)helper

line: 
mOpenPanel = [NSOpenPanel openPanel];