steps to reproduce

1. load the attached zul in IE11
2. drag the calendar event and move it to another day
   (if you set zoom level other than 100% e.g. 125%, it's easier to reproduce this bug)

current result

sometimes, the server throws the exception:

SEVERE:
java.lang.NumberFormatException: For input string: "335.6199951171875"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:492)
at java.lang.Integer.parseInt(Integer.java:527)
at org.zkoss.calendar.event.CalendarsEvent.getInt(CalendarsEvent.java:143)
at org.zkoss.calendar.event.CalendarsEvent.getUpdateEvent(CalendarsEvent.java:117)
at org.zkoss.calendar.Calendars.service(Calendars.java:938)
at org.zkoss.zk.ui.impl.DesktopImpl.service(DesktopImpl.java:710)
at org.zkoss.zk.ui.impl.UiEngineImpl.execUpdate(UiEngineImpl.java:1249)
at org.zkoss.zk.au.http.DHtmlUpdateServlet.process(DHtmlUpdateServlet.java:603)

root cause

• client side sends a double ( MouseEvent.pageX) and the component tries to parse it as an integer

debug information

• chrome and firefox don't have such issue