ValueField: Don't call setDisplayText() while typing

This would cause the cursor position to change. Instead, only the
property 'displayText' is updated.

Change-Id: Ie5c126ec0763e97d483f70774ca34071ae3ee5fe
diff --git a/org.eclipse.scout.rt.ui.html/src/main/js/scout/form/fields/ValueField.js b/org.eclipse.scout.rt.ui.html/src/main/js/scout/form/fields/ValueField.js
index e4e0a34..41265eb 100644
--- a/org.eclipse.scout.rt.ui.html/src/main/js/scout/form/fields/ValueField.js
+++ b/org.eclipse.scout.rt.ui.html/src/main/js/scout/form/fields/ValueField.js
@@ -53,7 +53,9 @@
   // trigger only if displayText has really changed
   if (this._checkDisplayTextChanged(displayText, whileTyping)) {
     if (whileTyping) {
-      this.setDisplayText(displayText, whileTyping);
+      // Don't call setDisplayText() to prevent re-rendering of display text (which is unnecessary and
+      // might change the cursor position).
+      this._callSetProperty('displayText', displayText);
     } else {
       this._parseAndSetValue(displayText); // this also calls setDisplayText()
     }
@@ -103,11 +105,7 @@
   this.trigger('displayTextChanged', event);
 };
 
-/**
- * Not used by acceptInput by purpose, because display text doesn't have to be rendered again.
- * May be used to just modify the display text without validation XXX
- */
-scout.ValueField.prototype.setDisplayText = function(displayText, whileTyping) {
+scout.ValueField.prototype.setDisplayText = function(displayText) {
   this.setProperty('displayText', displayText);
 };