Work around a FX/SWT bug for scrolling on Linux

Signed-off-by: Ulrich Schöpp <schoepp@fortiss.org>
Issue-Ref: 4183

org.fortiss.tooling.kernel.ui/META-INF/MANIFEST.MF

@@ -9,7 +9,8 @@ Require-Bundle: org.fortiss.tooling.common.ui;visibility:=reexport,
  org.eclipse.core.resources;visibility:=reexport,
  org.eclipse.emf.databinding;visibility:=reexport,
  org.eclipse.core.databinding.property;visibility:=reexport,
- com.google.guava;visibility:=reexport
+ com.google.guava;visibility:=reexport,
+ org.fortiss.tooling.base;bundle-version="2.20.0"
 Bundle-ActivationPolicy: lazy
 Bundle-RequiredExecutionEnvironment: JavaSE-11
 Bundle-Vendor: fortiss GmbH

org.fortiss.tooling.kernel.ui/src/org/fortiss/tooling/kernel/ui/extension/base/.ratings

@@ -4,7 +4,7 @@ EObjectActionBase.java dba517c7527d71637239483dbe15b447fd1e6b19 GREEN
 EReferenceListPropertySectionBase.java 7390dd7bfdc979e8ff0c5c30c67ab7b6c9d70c92 GREEN
 EReferencePropertySectionBase.java 0548da6778516003257f59d0b4c2b60d458be3b6 GREEN
 EditorBase.java 9c09fff92945256bb8680992ae7bb2c78f47b150 GREEN
-FXEditorBase.java 40caf638c7b4c02da5aece0d9d58883bce630e76 GREEN
+FXEditorBase.java 659e123d09f500a1df5aac41a4d4a52bc9cd9b10 YELLOW
 IListPropertySection.java 8bb00fe7959583e794ff9437b7a77404c9a9e70f GREEN
 LWFXEFEditorBase.java 467367f3e9dcf90eff57e268a7e12d8c9f33a836 GREEN
 ModelEditorBindingBase.java b9b1a1c5a48a6e677d1f57ad55a6126d9703c4b5 GREEN

org.fortiss.tooling.kernel.ui/src/org/fortiss/tooling/kernel/ui/extension/base/FXEditorBase.java

@@ -15,6 +15,8 @@
 +--------------------------------------------------------------------------*/
 package org.fortiss.tooling.kernel.ui.extension.base;
 
+import static org.fortiss.tooling.base.utils.SystemUtils.isLinuxPlatform;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -48,6 +50,20 @@ public abstract class FXEditorBase<T extends EObject> extends EditorBase<T>
 		Scene scene = new Scene(createSceneRoot());
 		canvas.setScene(scene);
 		getSite().setSelectionProvider(this);
+
+		// Work around a bug in FXCanvas or SWT on Linux, where
+		// scrolling does not work.
+		// On Linux, FXCanvas receives a start gesture event when
+		// the mouse is clicked. It disables scrolling while the
+		// gesture is ongoing. However, the gesture end event never
+		// arrives. As a result, scrolling is disabled after the first
+		// mouse click. This work-around simply filters out all gesture
+		// events, which should not be used in the FX part currently.
+		if(isLinuxPlatform()) {
+			canvas.getDisplay().addFilter(SWT.Gesture, e -> {
+				e.type = SWT.NONE;
+			});
+		}
 	}
 
 	/** Creates the root node of the scene. */