Edge: Freeze in Browser#evaluate() if evaluated script calls into SWT

[sratz]

Describe the bug
With Edge, when using browser.evaluate(script) and script somehow causing a callback into SWT, the evaluate() freezes / hangs in 100% CPU.

To Reproduce

@Test
public void test_EvaluateCallingIntoSwt() throws Exception {
	AtomicBoolean initialLoad = new AtomicBoolean();
	AtomicBoolean openWindowListenerCalled = new AtomicBoolean();
	browser.addProgressListener(ProgressListener.completedAdapter(e -> initialLoad.set(true)));
	browser.addOpenWindowListener(event -> {
		event.required = true; // block default
		openWindowListenerCalled.set(true);
	});
	browser.setText("""
			<button id="button" onClick="window.open('https://eclipse.org');">open eclipse.org</button>
			""");
	waitForPassCondition(initialLoad::get);

	browser.evaluate("""
				document.getElementById("button").click();
			""");

	waitForPassCondition(openWindowListenerCalled::get);
}

Expected behavior
Test succeeds with IE and Edge.

Actual behavior
Test hangs with Edge, succeeds with IE.
Stack trace shows:

Thread [main] (Suspended)	
	org.eclipse.swt.internal.win32.OS.PeekMessage(org.eclipse.swt.internal.win32.MSG, long, int, int, int) line: not available [native method]	
	org.eclipse.swt.browser.Edge.processNextOSMessage() line: 371	
	org.eclipse.swt.browser.Edge.callAndWait(java.lang.String[], java.util.function.ToIntFunction<org.eclipse.swt.internal.ole.win32.IUnknown>) line: 284	
	org.eclipse.swt.browser.Edge.evaluate(java.lang.String) line: 746	
	org.eclipse.swt.browser.Edge(org.eclipse.swt.browser.WebBrowser).evaluate(java.lang.String, boolean) line: 406	
	org.eclipse.swt.browser.Browser.evaluate(java.lang.String, boolean) line: 665	
	org.eclipse.swt.browser.Browser.evaluate(java.lang.String) line: 614	
	org.eclipse.swt.tests.junit.Test_org_eclipse_swt_browser_Browser.test_EvaluateCallingIntoSwt() line: 2700	

Environment:

1. Select the platform(s) on which the behavior is seen:

• • All OS
• • Windows / Edge
• • Linux
• • macOS

2. Additional OS info (e.g. OS version, Linux Desktop, etc)

Additional context
This is a side-effect of #660, where inside Edge.callAndWait()
if (!display.readAndDispatch()) display.sleep();
was replaced with
processNextOSMessage();.

@HeikoKlare:
PR #660 suggest that this was to avoid a out-of-handles during initialization, i.e. inside createEnvironment(), but it also affects the evaluate() call negatively.
Do you think it would be reasonable to keep using display.readAndDispatch() in the latter?

[HeikoKlare]

Thank you for this report, @sratz! We are currently investigating potential reasons for Edge blocking the UI thread (according to eclipse-platform/eclipse.platform.ui#2734) starting with this PR:

• WebViewWrapperFuture handling on job termination timeout #1752

I also pointed to the calls to processNextOSMessage() there (#1752 (review)) as they might be blocking the UI thread. Now it's nice to have an actual reproducer of a potential issue from you!

In my opinion, we could/should replace all the calls to processNextOSMessage() and just do the previous if (!display.readAndDispatch()) display.sleep() again, as in every case (in particular the initialization) this is now run inside a loop anyway (as the initialization logic has changed and been made completely asynchronous since back then). So there is no need for peeking a message anymore.

[HeikoKlare]

I've created a draft PR with the idea for the improvement:

• [Win32] Spin event loop in Edge instead of only processing OS messages #1773