Fixes bug #780 After undo (ctrl-Z), text insertion point jumps to the start (#785)

Author: Jugen

Diff for: richtextfx/src/integrationTest/java/org/fxmisc/richtext/api/UndoManagerTests.java

@@ -16,6 +16,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 @RunWith(NestedRunner.class)
 public class UndoManagerTests {
@@ -40,6 +41,22 @@ public void incoming_change_is_not_merged_after_period_of_user_inactivity() {
             assertEquals("", area.getText());
         }
 
+        @Test  // After undo, text insertion point jumps to the start of the text area #780
+        public void undo_leaves_correct_insertion_point() {
+            long periodOfUserInactivity = UndoUtils.DEFAULT_PREVENT_MERGE_DELAY.toMillis() + 300L;
+
+            write("abc def ");
+            sleep(periodOfUserInactivity);
+
+            write("xyz");
+            interact(area::undo);
+
+            write('g');
+
+            sleep(periodOfUserInactivity);
+            assertTrue(area.getText().endsWith("g"));
+        }
+
         @Test
         public void testUndoWithWinNewlines() {
             String text1 = "abc\r\ndef";

Diff for: richtextfx/src/main/java/org/fxmisc/richtext/SelectionImpl.java

@@ -269,9 +269,9 @@ public SelectionImpl(String name, GenericStyledArea<PS, SEG, S> area, int startP
                         // (prevents a StringIndexOutOfBoundsException because
                         // end is one char farther than area's length).
 
-                        if (getLength() < getEndPosition()) {
-                            finalStart = getLength();
-                            finalEnd = getLength();
+                        if (getEndPosition() > 0) {
+                            finalStart = area.getLength();
+                            finalEnd = finalStart;
                         }
                     }
                 }