Merge pull request #481 from scijava/show-ui-edt

Closes imagej/imagej-legacy#306

Author: hinerm

Diff for: src/main/java/org/scijava/ui/DefaultUIService.java

@@ -32,6 +32,7 @@
 import java.awt.GraphicsEnvironment;
 import java.io.File;
 import java.io.FileFilter;
+import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -161,10 +162,25 @@ public void showUI(final String name) {
 	@Override
 	public void showUI(final UserInterface ui) {
 		log.debug("Launching user interface: " + ui.getClass().getName());
-		ui.show();
-		// NB: Also show all the current displays.
-		for (final Display<?> display : displayService.getDisplays()) {
-			ui.show(display);
+		Runnable showUI = () -> {
+			ui.show();
+			// NB: Also show all the current displays.
+			for (final Display<?> display : displayService.getDisplays()) {
+				ui.show(display);
+			}
+		};
+
+		// Dispatch on EDT if necessary
+		if (ui.requiresEDT()) {
+			try {
+				threadService.invoke(showUI);
+			}
+			catch (InterruptedException | InvocationTargetException e) {
+				throw new RuntimeException(e);
+			}
+		}
+		else {
+			showUI.run();
 		}
 		eventService.publish(new UIShownEvent(ui));
 	}