Fixes cursor blinking in the QComboBox when it becomes editable while having the focus.
Fixes cursor blinking in the QComboBox when it becomes editable while having the focus.

The lineedit has the focus because it becomes focusproxy of the QComboBox.
But the focusInEvent is not called because the combobox has already
the focus when setFocusProxy is called.
Workaround that in the show event.

Task-number: QTBUG-1949
Reviewed-by: Thierry

igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt