add some comments (cherry picked from commit 4f66b3c550ca1c90c33952ad8603cc6c1a702280)
add some comments
(cherry picked from commit 4f66b3c550ca1c90c33952ad8603cc6c1a702280)

pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,KDE/qt,radekp/qt,igor-sfdc/qt-wk,radekp/qt,KDE/qt,radekp/qt,RLovelett/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,radekp/qt,radekp/qt,RLovelett/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,RLovelett/qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,radekp/qt,KDE/qt,RLovelett/qt,radekp/qt,RLovelett/qt,KDE/qt,radekp/qt,KDE/qt,RLovelett/qt,igor-sfdc/qt-wk,RLovelett/qt,RLovelett/qt,RLovelett/qt,KDE/qt,igor-sfdc/qt-wk,radekp/qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,KDE/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,KDE/qt,radekp/qt