[news.eclipse.platform.swt] Opening OS dialog stalls GUI events

[Joshua Salit <jrsalit@xxxxxxxxxx>]

Hi,
When you open an operating system supplied dialog, such as 
swt.widgets.FileDialog (on Windows, at least, it's provided by a native 
function org.eclipse.swt.internal.win32.GetOpenFileNameA()), the event 
thread seems to stall until the dialog has closed.

Now, I can sort of understand this would be out of Eclipse's control, as 
the Windows dialog is modal and probably just somehow stops the 
display's event thread from getting events.  But I'll give an example of 
an application where this becomes a little annoying - imagine something 
like a performance monitor, showing graphs/charts that are constantly 
updated.  As soon as you open a dialog, these graphs stop updating until 
the dialog is closed.  Not SO bad, as long as the user realizes this is 
happening.  But if the user happened to not notice that the charts in 
the background were no longer updating, and a critical situation arose 
in the charts that they didn't/couldn't see, then this situation becomes 
a little worse.

I've attached an example to reproduce this problem...it's a modification 
of a few snippets, which starts adding items to a table in a thread, and 
then after 25 items have been added, it pops up a FileDialog.  The thing 
to notice is that while the FileDialog is opened, no more items are 
(visibly) added to the table.  When the FileDialog is closed, the table 
catches up with itself pretty quickly.

Sorry if the code is a bit messy, it's short at least.

Although I'm pretty sure this is currently working-as-designed, it's 
causing a bit of a problem for me so I thought I'd ask.  I'd appreciate 
hearing what others think of this...if there's something obvious I am 
missing that would allow me to work around this, or if this is worth 
opening a bug report for, etc..

Thank you!
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.*;

public class TableDialogTest {

public static void main (String [] args) {
	final Display display = new Display ();
	final Shell shell = new Shell (display);
	GridLayout gl = new GridLayout(1, true);
	shell.setLayout(gl);
	final Table table = new Table (shell, SWT.MULTI | SWT.CHECK | SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL);
	table.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));		
	
	for (int i=0; i<5; i++) {
		TableItem item = new TableItem (table, SWT.NONE);
		item.setText("12345678901234567890123456789");
	}
	
	Thread thread = new Thread () {
		public void run () {
			for (int i=0; i<20000; i++) {			
				if (table.isDisposed ()) return;
				display.asyncExec (new Runnable () {
					public void run () {
						if (table.isDisposed ()) return;
						
						if(table.getItemCount() == 25) {
							FileDialog fd = new FileDialog(shell, SWT.OPEN);			
							fd.open();
						}
						
						TableItem item = new TableItem (table, SWT.NONE);
						item.setText("12345678901234567890123456789");
					}
				});
			}
		}
	};
	thread.start();
	
	table.setSize(table.computeSize(SWT.DEFAULT, 200));
	shell.pack ();
	shell.open ();
	
	while (!shell.isDisposed ()) {
		if (!display.readAndDispatch ()) display.sleep ();
	}
	display.dispose ();
}
}