GWT - Loading screen onButtonClick - gwt

Question

I'm trying to create a loading screen (in this case a PopUp Panel) everytime I click on a button and to hide the screen when the processing is done.
But the problem is that the loading screen never appears.
If I delete the line that hides the loading screen:
//HIDES THE LOADING POPUP
closeLoadingFilter();
The loading screen appears but only until everything finished processing. (not inmediately after I click the button).
I think all the processing in the button handler must be completed before anything appears on the screen. So when the processing is complete the popup is hidden before it was ever showed on the screen.
How can I solve this problem. By the way there is no Async call in the processing, everything is in-memory processing and the drawing of google visualizations with the in-memory information
Thank you all
Here is the code:
buttonFilter.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
//SHOWS THE LOADING POPUP
showLoadingFilter();
//ALL THIS TAKES AROUND 4 SECONDS
//THERE IS NO ASYNC CALL
//EVERYTHING IS IN-MEMORY PROCESSING
//AND DRAWING OF GOOGLE VISUALIZATION
listValues.clear();
listFields.clear();
CreateListFiltersSingle();
GetFilterSingleOptions();
RunFilter(dashboardProductos);
DrawVisualizations2();
//HIDES THE LOADING POPUP
closeLoadingFilter();
}
})
public void showLoadingFilter() {
popupFilterLoading.clear();
popupFilterLoading.add(new Label("Please wait"));
popupFilterLoading.setGlassEnabled(true);
popupFilterLoading.center();
isFilterLoading = true;
popupFilterLoading.show();
}
public void closeLoadingFilter() {
if (isFilterLoading) {
popupFilterLoading.hide();
isFilterLoading = false;
}
}

Answer 1

You can call methods asynchronously using a scheduler. The code below might solve your problem.
submit.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
showLoadingFilter();
// Waits for the loading pop-up to be displayed before starting anything
Scheduler.get().scheduleDeferred(new ScheduledCommand() {
#Override
public void execute() {
listValues.clear();
listFields.clear();
CreateListFiltersSingle();
GetFilterSingleOptions();
RunFilter(dashboardProductos);
DrawVisualizations2();
closeLoadingFilter();
}
});
}