Very nearly working

src/tab.rs

@@ -555,8 +555,7 @@ impl Tab {
                         terminal.y() + 1,
                         terminal.x() + 1,
                         pad_to_size(&vte_output, terminal.rows(), terminal.columns())
-                    )
+                    ).expect("cannot write to stdout");
-                    .expect("cannot write to stdout");
                 }
             }
         }

src/terminal_pane/terminal_pane.rs

@@ -1,6 +1,6 @@
 #![allow(clippy::clippy::if_same_then_else)]
 
-use crate::tab::Pane;
+use crate::{tab::Pane, utils::shared::ansi_len};
 use ::nix::pty::Winsize;
 use ::std::os::unix::io::RawFd;
 use ::vte::Perform;

src/utils/shared.rs

@@ -1,15 +1,15 @@
-use std::iter;
+use std::{iter, str::from_utf8};
 
 use strip_ansi_escapes::strip;
 
 // FIXME: Should this be an extension trait? Or here at all?
 pub fn ansi_len(s: &str) -> usize {
-    strip(s.as_bytes()).unwrap().len()
+    from_utf8(&strip(s.as_bytes()).unwrap()).unwrap().chars().count()
 }
 
 pub fn pad_to_size(s: &str, rows: usize, columns: usize) -> String {
     s.lines()
-        .map(|l| [l, &str::repeat(" ", dbg!(columns) - dbg!(ansi_len(l)))].concat())
+        .map(|l| [l, &str::repeat(" ", columns - ansi_len(l))].concat())
         .chain(iter::repeat(str::repeat(" ", columns)))
         .take(rows)
         .collect::<Vec<_>>()