ADDITIONAL SYSTEM INFORMATION :
Windows 10 and Windows 11 (and probably all previous Window)

A DESCRIPTION OF THE PROBLEM :
 -Dsun.java2d.uiScale=x with x different than 1.0 doesn't scale correctly the tabulator in javax.swing.text.StyledDocument (Presented in JTextPane). Even with a x =1.01 ,

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
run the source code below with
java -Dsun.java2d.uiScale=1.0 Example
java -Dsun.java2d.uiScale=1.01 Example
compare the results

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
All columns should contain a value

ACTUAL -
The last column Col5 contains no entry for the line starting with "a" where the distinct "c" and "11" are erroneously concatenated in Col3 instead of being separated with a tabulator

---------- BEGIN SOURCE ----------
import java.awt.BorderLayout;
import javax.swing.text.StyleConstants;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.AttributeSet;
import javax.swing.text.StyleContext;
import javax.swing.text.StyleContext;
import javax.swing.text.TabSet;
import javax.swing.text.TabStop;
import javax.swing.*;

/** Buggy text presentation
java -Dsun.java2d.uiScale=1.01 Example
Expected result: All columns should contain an entry
Actual Result: The last column Col5 contains no entry for the line starting with "a".
*/
public class Example {
   public static void main(String[] args) {
      JTextPane tp = new JTextPane();
      
      {
         // setting tabs
        int ncols = 5;
        TabStop[] tabs = new TabStop[ncols]; //BUG: needs more
        for(int i=0; i<tabs.length; i++)
        {
           //fails with right and decimal
           // success with left and center and bar
           int align = TabStop.ALIGN_DECIMAL;
           tabs[i] = new TabStop(90*(i+1), align, TabStop.ALIGN_DECIMAL);
        }
        TabSet tabset = new TabSet(tabs);
        StyleContext sc = StyleContext.getDefaultStyleContext();
        AttributeSet aset = sc.addAttribute(SimpleAttributeSet.EMPTY,
        StyleConstants.TabSet, tabset);
        tp.setParagraphAttributes(aset, false);
      }
      // writing some content
      StringBuilder sb = new StringBuilder();
      sb.append("Illustration of tab align_decimal bug with -Dsun.java2d.uiScale="+System.getProperty("sun.java2d.uiScale")+"\n");
      sb.append("Quick bug observation #1: the last column should contain elements. c and 11 are in 2 separate columns.\n");
      
      sb.append("observation #2: place the caret before the <a> and insert whitespaces.\n");
      sb.append("\n\tCol 1\tCol 2\tCol 3\tCol 4\tCol 5");
      sb.append("\n\ta\tb\tc\t11\t-1221");
      sb.append("\n\t0\t1\t2\t3\t2.22");
      sb.append("\n\td\te\tf\t1.23\t-3.33");
      sb.append("\n\t0.0123\t-1.2341\t2.344\t3.1232\tend");
      tp.setText( sb.toString() );

      JFrame fr = new JFrame("Bug example");
      fr.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      fr.getContentPane().add( new JScrollPane(tp), BorderLayout.CENTER);
      fr.setSize(800,500);
      fr.setVisible(true);
   }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
use Align_CENTER or ALING_LEFT instead, but this is only a bugfix.

FREQUENCY : always