[3924] Fix small bugs in fx diagram editor

Fixes various minor things that came up when updating the security plugin.

org.fortiss.tooling.common.ui/src/org/fortiss/tooling/common/ui/javafx/lwfxef/visual/elliptic/EllipticBorderLocation.java

@@ -51,6 +51,8 @@ public final class EllipticBorderLocation {
 	/**
 	 * Returns the location computed from this {@link EllipticBorderLocation} relative to the
 	 * ellipse center.
+	 * TODO(JE): leads to java.lang.ArithmeticException: / by zero if cos is 0. What is the
+	 * difference to the existing code? Why is an adaption needed?
 	 */
 	public DiagramCoordinate getLocation() {
 		double angle = Math.PI * angleInDegree / 180;