diff --git a/examples/show_multi_bar.py b/examples/show_multi_bar.py
index 3399cb9..142411d 100644
--- a/examples/show_multi_bar.py
+++ b/examples/show_multi_bar.py
@@ -1,6 +1,8 @@
 import random
 import time
 
+import numpy as np
+
 import scgenerator as sc
 
 SIZE = 100
@@ -8,11 +10,15 @@ SIZE = 100
 
 def compute_stuff(num: int, pbar: sc.threading.Multibar):
     speed = random.random() * 5
+    out = 0
     for i in pbar(range(SIZE), desc=f"num {num}"):
-        time.sleep(0.05 * speed * random.random())
+        # time.sleep(0.01 * speed * random.random())
+        out += np.abs(np.subtract.outer(np.random.rand(1 << 13), np.random.rand(1 << 13))).min()
+        if i == 32:
+            pbar.print(f"reached 32 in {num}")
         # if random.random() > 0.98:
         #     print(f"some text {i}")
-    return num
+    return out
 
 
 def main():
diff --git a/pyproject.toml b/pyproject.toml
index 2a4cdc0..b092b2e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "scgenerator"
-version = "0.4.4"
+version = "0.4.5"
 description = "Simulate nonlinear pulse propagation in optical fibers"
 readme = "README.md"
 authors = [{ name = "Benoit Sierro", email = "benoit.sierro@iap.unibe.ch" }]
diff --git a/src/scgenerator/threading.py b/src/scgenerator/threading.py
index eb11f77..4c17398 100644
--- a/src/scgenerator/threading.py
+++ b/src/scgenerator/threading.py
@@ -98,6 +98,7 @@ class DelayedTqdm:
         self.label = name
         if self.bar is not None:
             self.bar.set_description(self.label)
+            self.bar.refresh()
 
 
 class PositionGetter:
@@ -127,7 +128,12 @@ class MultibarThread(Thread):
     sub_pbars: list[DelayedTqdm]
 
     def __init__(
-        self, n_bars: int, n_show: int, queue: Queue, default_total: int | float | None = None
+        self,
+        n_bars: int,
+        n_show: int,
+        queue: Queue,
+        default_total: int | float | None = None,
+        desc: str | None = None,
     ):
         super().__init__()
         self.queue = queue
@@ -136,7 +142,10 @@ class MultibarThread(Thread):
 
         self.sub_pbars = [DelayedTqdm(pos_getter, total=default_total) for _ in range(n_bars)]
         self.main_pbar = tqdm(
-            total=sum((bar.total or 0) for bar in self.sub_pbars), position=0, colour="green"
+            total=sum((bar.total or 0) for bar in self.sub_pbars),
+            position=0,
+            colour="green",
+            desc=desc,
         )
         self.started = False
         self.finished = False
@@ -233,8 +242,6 @@ class Multibar:
 
     def close(self):
         self.queue.put(PBarMessage(self.id, Command.FINISHED))
-        # sys.stdout = sys.__stdout__
-        # sys.stderr = sys.__stderr__
 
     def __enter__(self):
         return self
@@ -272,6 +279,12 @@ class Multibar:
         self.queue.put(PBarMessage(self.id, Command.FINISHED))
         self.finished = True
 
+    def set_description(self, desc: str):
+        self.queue.put(PBarMessage(self.id, Command.NEW_NAME, desc))
+
+    def print(self, msg: str):
+        self.queue.put(PBarMessage(self.id, Command.PRINT, msg))
+
     def check_start_finish(self):
         if self.finished:
             raise ValueError(f"{self.__class__.__name__} {self.id} has already finished")
@@ -306,10 +319,12 @@ class MultibarManager:
         yield from self.mbars
 
 
-def multibar(n_tasks: int, n_show: int, n_pertask: int | float | None = None) -> MultibarThread:
+def multibar(
+    n_tasks: int, n_show: int, n_pertask: int | float | None = None, desc: str | None = None
+) -> MultibarThread:
     manager = multiprocessing.Manager()
     queue = manager.Queue()
-    thread = MultibarThread(n_tasks, n_show, queue, n_pertask)
+    thread = MultibarThread(n_tasks, n_show, queue, n_pertask, desc)
 
     mbars = [Multibar(i, queue, n_pertask) for i in range(n_tasks)]
     return MultibarManager(thread, queue, mbars)
@@ -321,12 +336,13 @@ def apply_with_progress(
     n_cpu: int | None = None,
     n_pertask: int | None = None,
     unpack: bool = True,
+    desc: str | None = None,
 ) -> list[T]:
     args = list(args)
     n_cpu = n_cpu or multiprocessing.cpu_count()
     with (
         multiprocessing.Pool(n_cpu) as pool,
-        multibar(n_tasks=len(args), n_show=n_cpu, n_pertask=n_pertask) as bars,
+        multibar(n_tasks=len(args), n_show=n_cpu, n_pertask=n_pertask, desc=desc) as bars,
     ):
         if unpack:
             all_args = ((*arg, bars[i]) for i, arg in enumerate(args))
diff --git a/tests/test_io_handlers.py b/tests/test_io_handlers.py
index b84e65b..dad107f 100644
--- a/tests/test_io_handlers.py
+++ b/tests/test_io_handlers.py
@@ -152,6 +152,11 @@ def test_zip_bundle(tmp_path: Path):
     assert prop3.parameters.effective_area_file.path == new_aeff_path.name
     assert prop3.parameters.effective_area_file.prefix == "zip"
 
+    assert (
+        DataFile(None, new_disp_path, None).load_bytes()
+        == prop3.parameters.dispersion_file.load_bytes()
+    )
+
     with ZipFile(tmp_path / "file3.zip", "r") as zfile:
         with zfile.open(new_aeff_path.name) as file:
             assert file.read() == new_aeff_path.read_bytes()