IDEA-229577: Marked i3wm as GravityBuggy

src/java.desktop/unix/classes/sun/awt/X11/XWM.java

@@ -149,6 +149,8 @@ final class XWM
               return "XMonad";
           case AWESOME_WM:
               return "Awesome";
+          case XWM.I3_WM:
+              return "I3WM";
           case UNDETERMINED_WM:
           default:
               return "Undetermined WM";
@@ -1466,6 +1468,8 @@ final class XWM
           case XWM.ENLIGHTEN_WM:
               /* At least E16 is buggy. */
               return true;
+          case XWM.I3_WM:
+              return true;
           default:
               return false;
         }