widget: fix moveLines residual x offset calculation

Commit c22138f5f broke it, this change fixes it.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

widget/editor.go

@@ -398,7 +398,7 @@ func (e *Editor) moveLines(distance int, selAct selectionAction) {
 	pos := e.closestPosition(combinedPos{lineCol: screenPos{Y: caretStart.lineCol.Y + distance}})
 	pos = e.closestPosition(combinedPos{x: x, y: pos.y})
 	e.caret.start = pos.runes
-	e.caret.xoff = x - caretStart.x
+	e.caret.xoff = x - pos.x
 	e.updateSelection(selAct)
 }
 

widget/editor_test.go

@@ -120,6 +120,14 @@ func TestEditor(t *testing.T) {
 			}
 		}
 	}
+
+	// Test that moveLine applies x offsets from previous moves.
+	e.SetText("long line\nshort")
+	e.SetCaret(0, 0)
+	e.moveEnd(selectionClear)
+	e.moveLines(+1, selectionClear)
+	e.moveLines(-1, selectionClear)
+	assertCaret(t, e, 0, utf8.RuneCountInString("long line"), len("long line"))
 }
 
 func TestEditorDimensions(t *testing.T) {