user interface - WPF forcing GUI update using Dipatcher -

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i need show custom control (a clock rotating hands) , replace mouse cursor, problem if write:

me.gridscreen.visibility = visibility.visible ' operations takes 1 second me.gridscreen.visibility = visibility.hidden (gridscreen grid contains user-control)

obviously can see nothing, because update of ui happens @ end of procedure. have tried me.updatelayout(), doesn't work.

i have tryed use dispacker in many way none works :-(

this lost attempt:

(ucurclock usercontrol, gridscreen grid placed @ top-level in window, trasparent background, contains usercontrol)

private sub showclock()     dim thread = new system.threading.thread(addressof showclockintermediate)     thread.start() end sub  private sub hideclock()     dim thread = new system.threading.thread(addressof hideclockintermediate)     thread.start() end sub  private sub showclockintermediate()     me.dispatcher.begininvoke(dispatcherpriority.normal, _         new action(addressof showclockfinale)) end sub  private sub hideclockintermediate()     me.dispatcher.begininvoke(dispatcherpriority.normal, _         new action(addressof hideclockfinale)) end sub  private sub showclockfinale()     dim pt point = mouse.getposition(nothing)     me.ucurclock.margin = new thickness(pt.x - 9, pt.y - 9, 0, 0)     me.gridscreen.visibility = visibility.visible     me.cursor = cursors.none     me.updatelayout() end sub  private sub hideclockfinale()     me.gridscreen.visibility = visibility.hidden     me.cursor = cursors.arrow     me.updatelayout() end sub  private sub u_mousemove(byval sender system.object, _     byval e mouseeventargs) handles gridscreen.mousemove      dim pt point = e.getposition(nothing)     me.ucurclock.margin = new thickness(pt.x - 9, pt.y - 9, 0, 0)      e.handled = true end sub  private sub u_mouseenter(byval sender system.object, _     byval e mouseeventargs) handles gridscreen.mouseenter      me.ucurclock.visibility = visibility.visible      e.handled = true end sub  private sub u_mouseleave(byval sender system.object, _     byval e mouseeventargs) handles gridscreen.mouseleave      me.ucurclock.visibility = visibility.hidden      e.handled = true end sub

pileggi

the problem not composition of messages being executed on dispatcher, it's you're executing long-running work on dispatcher @ all. must ensure long-running/potentially blocking operations executed on background thread. easiest way backgroundworker component.

excuse c#:

var backgroundworker = new backgroundworker();  backgroundworker.dowork += delegate {     // long running work goes here }; backgroundworker.runworkercompleted += delegate {     // change cursor normal here };  // change cursor busy here  // kick off background task backgroundworker.runworkerasync();

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