JLine3 Status Bar Vertical Resize Bug

[Abdelilah-AIT-HAMOU]

used AI to summarize the issue :

Summary

When a terminal with a JLine3 Status bar is resized vertically, the old status bar content remains visible at the old position until the next user input (keystroke). This creates a visual artifact where multiple status bars appear to be present.

Expected Behavior

On vertical terminal resize, the Status bar should:

1. Clear from its old position
2. Immediately appear at the new bottom position
3. No visual artifacts should remain

Actual Behavior

On vertical terminal resize:

1. New status bar appears at the correct new position
2. Old status bar content remains visible at the old position
3. Old status bar only disappears when user presses a key or types

Reproducible Test Case

MinimalStatusBarBug.java

Minimal test using standard JLine3 APIs following official documentation. This demonstrates the bug with vanilla JLine3 - no custom code or workarounds.

Compile:

javac -cp "jline3/terminal/target/jline-terminal-3.30.4.jar:jline3/reader/target/jline-reader-3.30.4.jar" MinimalStatusBarBug.java

Run:

java -cp ".:jline3/terminal/target/jline-terminal-3.30.4.jar:jline3/reader/target/jline-reader-3.30.4.jar" MinimalStatusBarBug

Steps to reproduce:

1. Run the program
2. Observe status bar at bottom showing "Status Bar - Resize the terminal vertically to see the bug"
3. Resize terminal vertically (drag window taller or shorter)
4. BUG: Old status bar remains visible at old position
5. Press Enter - the old status bar disappears
6. Type quit to exit

##code :

// Source code is decompiled from a .class file using FernFlower decompiler (from Intellij IDEA).
import java.io.IOException;
import java.util.Collections;
import org.jline.reader.LineReader;
import org.jline.reader.LineReaderBuilder;
import org.jline.terminal.Terminal;
import org.jline.terminal.TerminalBuilder;
import org.jline.utils.AttributedString;
import org.jline.utils.Status;

public class MinimalStatusBarBug {
   public MinimalStatusBarBug() {
   }

   public static void main(String[] var0) throws IOException {
      Terminal var1 = TerminalBuilder.builder().system(true).build();
      LineReader var2 = LineReaderBuilder.builder().terminal(var1).appName("MinimalTest").build();
      Status var3 = Status.getStatus(var1, true);
      var3.update(Collections.singletonList(new AttributedString("Status Bar - Resize the terminal vertically to see the bug")));
      System.out.println("=== Minimal JLine3 Status Bar Bug Reproduction ===");
      System.out.println();
      System.out.println("Bug reproduction steps:");
      System.out.println("1. You should see a status bar at the bottom");
      System.out.println("2. Resize the terminal vertically (make it taller or shorter)");
      System.out.println("3. BUG: The old status bar stays at its old position");
      System.out.println("4. Press Enter - the old status bar disappears");
      System.out.println();
      System.out.println("Type 'quit' to exit");
      System.out.println();

      while(true) {
         String var4 = var2.readLine("> ");
         if (var4 == null || "quit".equalsIgnoreCase(var4.trim())) {
            var3.update(Collections.emptyList());
            var1.close();
            return;
         }

         System.out.println("Input: " + var4);
      }
   }
}

[gnodet]

Haven't had time to look at it yet, will try next week.

[Abdelilah-AIT-HAMOU]

thank you

[gnodet]

Which terminal emulator are you using ? I've tried on the two I usually use (Terminal.app and Ghostty) and haven't reproduced the problem. I end up with a mostly blank terminal, the status bar at the bottom, the prompt at the top.

[Abdelilah-AIT-HAMOU]

i tried all the terminal ( mac terminal , iterm , ghosty ) and i can produce the issue in all of them.

[gnodet]

i tried all the terminal ( mac terminal , iterm , ghosty ) and i can produce the issue in all of them.

Can you provide a screenshot please ?

[Abdelilah-AIT-HAMOU]

Hey @gnodet,

I was using a version that already included this change:
https://github.com/jline/jline3/pull/1386/files

That’s why I was seeing this behavior.

This change prevents the screen from being cleared on resize. However, the downside is that it clears the text the same way Ctrl+K does, not like Ctrl+L. As a result, when I scroll up, the previous text is gone, which is really problematic.

Without this change, the status bar is redrawn correctly, but the screen still gets cleared on resize.

I logged this issue a while ago here:
#1386

Could you help fixing this? a middle solution that avoids clearing the screen on resize while preserving the same status bar redrawing behavior.

[Abdelilah-AIT-HAMOU]

when i launch , you see there's text

then resize applied : clears the screen

when you scroll up to see old text : it's deleted ( i think it has to do with the scroll region cursor going up and overriding text up eachtime you resize ( each winch pixel ) . because you will see many lines added and the scrolling bar at the side changing to contain more text in the window , so this resizing is causing adding empty lines and overriding previous text

q

[Abdelilah-AIT-HAMOU]

Any Comment @gnodet ?

[gnodet]

Any Comment @gnodet ?

I'm working on it.