Fix NEWT EDTUtil Deadlock on EDTUtil.start()

DisplayImpl.runOnEDTIfAvail(..) issues EDTUtil.start()
while holding it's object-lock - if the EDT is not running,
then invokes the given task.

EDTUtil.start() impl. holds it's own edt-lock
while starting, then releases it's edt-lock while issuing a null-task.

If another thread injects a blocking task right in-between
which also acquires the display's object-lock it deadlocks.

Simply remove issuing the null-task, so EDTUtil.start()
can return immediatly (releasing edt-lock)
and allowing DisplayImpl.runOnEDTIfAvail(..)
also to release it's object-lock.

The other threads task then can be executed,
where the 'starting task' would come second - which is OK,
even though a rare occasion.

Above situation was triggered via AWT/NEWT reparenting w/ forced recreation
via TestParenting01dAWT.

+++

The null-task at EDTUtil.start() was remaining code to ensure
that the EDT completed starting, which is redundant.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/newt/classes/com/jogamp/newt/util/EDTUtil.java b/src/newt/classes/com/jogamp/newt/util/EDTUtil.java
index 582dc3e1f..58aa67105 100644
--- a/src/newt/classes/com/jogamp/newt/util/EDTUtil.java
+++ b/src/newt/classes/com/jogamp/newt/util/EDTUtil.java
@@ -71,13 +71,13 @@ public interface EDTUtil {
      * and the caller should wait {@link #waitUntilStopped() until it's stopped}.
      * </p>
      *
-     * @return true if EDT has been successfully restarted, otherwise false
      * @throws IllegalStateException if EDT is running and not subject to be stopped, i.e. {@link #isRunning()} returns true
+     * @throws RuntimeException if EDT could not be started
      *
      * @see #invokeStop(boolean, java.lang.Runnable)
      * @see #waitUntilStopped()
      */
-    public boolean start() throws IllegalStateException;
+    public void start() throws IllegalStateException;
 
     /**
      * Returns true if the current thread is the event dispatch thread (EDT).