src/java.desktop/share/classes/javax/swing/text/PlainView.java

@@ -644,11 +644,11 @@
      */
     public float nextTabStop(float x, int tabOffset) {
         if (tabSize == 0) {
             return x;
         }
-        float ntabs = (x - tabBase) / tabSize;
+        int ntabs = ((int) x - tabBase) / (int)tabSize;        
         return tabBase + ((ntabs + 1) * tabSize);
     }
 
     // --- local methods ------------------------------------------------