webview fails on desktop mode after updating trame

[HametAl]

Hi,

After updating trame, I can't run trame with exec_mode="desktop". Please see the attached screenshot for the error.

Regards,
HA

[jourdain]

Do you have a list of version of your various packages. Ideally with what works, vs what doesn't?

[jourdain]

Just tried the following and it is working

uv venv -p 3.12 test-venv
source test-venv/bin/activate
uv pip install "trame[app]" trame-vuetify trame-vtk

python -m trame.app.demo --app

And here is what got installed

 + aiohappyeyeballs==2.6.2
 + aiohttp==3.14.1
 + aiosignal==1.4.0
 + attrs==26.1.0
 + bottle==0.13.4
 + frozenlist==1.8.0
 + idna==3.18
 + more-itertools==11.1.0
 + msgpack==1.2.1
 + multidict==6.7.1
 + propcache==0.5.2
 + proxy-tools==0.1.0
 + pyobjc-core==12.2
 + pyobjc-framework-cocoa==12.2
 + pyobjc-framework-quartz==12.2
 + pyobjc-framework-security==12.2
 + pyobjc-framework-uniformtypeidentifiers==12.2
 + pyobjc-framework-webkit==12.2
 + pywebview==6.2.1
 + pyyaml==6.0.3
 + trame==3.13.2
 + trame-client==3.13.2
 + trame-common==1.2.4
 + trame-server==3.12.5
 + trame-vtk==2.11.12
 + trame-vuetify==3.2.2
 + typing-extensions==4.15.0
 + wslink==2.5.7
 + yarl==1.24.2

[HametAl]

I am using vtklocal, would that be the cause? I have these installed:

Package Version

---

aiofiles 24.1.0
aiohappyeyeballs 2.6.1
aiohttp 3.13.3
aiosignal 1.4.0
altgraph 0.17.5
annotated-doc 0.0.4
annotated-types 0.7.0
anyio 4.12.1
argon2-cffi 25.1.0
argon2-cffi-bindings 25.1.0
arrow 1.4.0
asttokens 3.0.1
async-lru 2.3.0
asyncer 0.0.12
attrs 25.4.0
audioop-lts 0.2.2
babel 2.18.0
beautifulsoup4 4.15.0
bleach 6.4.0
bottle 0.13.4
brotli 1.2.0
CacheControl 0.14.4
certifi 2026.1.4
cffi 2.0.0
charset-normalizer 3.4.4
click 8.3.1
clr_loader 0.2.10
colorama 0.4.6
coloredlogs 15.0.1
comm 0.2.3
contourpy 1.3.3
cryptography 46.0.4
cycler 0.12.1
cyclopts 4.10.1
debugpy 1.8.20
decorator 5.2.1
defusedxml 0.7.1
docstring_parser 0.17.0
docutils 0.22.4
executing 2.2.1
fastapi 0.128.0
fastjsonschema 2.21.2
ffmpy 1.0.0
filelock 3.20.3
filetype 1.2.0
firebase_admin 7.1.0
flatbuffers 25.12.19
fonttools 4.61.1
fqdn 1.5.1
frozenlist 1.8.0
fsspec 2026.1.0
google-api-core 2.29.0
google-auth 2.48.0
google-cloud-core 2.5.0
google-cloud-firestore 2.23.0
google-cloud-storage 3.8.0
google-crc32c 1.8.0
google-resumable-media 2.8.0
googleapis-common-protos 1.72.0
gradio 6.5.1
gradio_client 2.0.3
groovy 0.1.2
grpcio 1.76.0
grpcio-status 1.76.0
h11 0.16.0
h2 4.3.0
hf-xet 1.2.0
hpack 4.1.0
httpcore 1.0.9
httpx 0.28.1
huggingface_hub 1.3.7
humanfriendly 10.0
hyperframe 6.1.0
idna 3.11
ImageIO 2.37.2
intel-cmplr-lib-ur 2025.3.2
intel-openmp 2025.3.2
ipykernel 7.1.0
ipython 9.9.0
ipython_pygments_lexers 1.1.1
ipywidgets 8.1.8
isoduration 20.11.0
jedi 0.19.2
Jinja2 3.1.6
json5 0.14.0
jsonpointer 3.1.1
jsonschema 4.26.0
jsonschema-specifications 2025.9.1
jupyter_client 8.8.0
jupyter_core 5.9.1
jupyter-events 0.12.1
jupyter-lsp 2.3.1
jupyter_server 2.19.0
jupyter_server_terminals 0.5.4
jupyterlab 4.5.8
jupyterlab_pygments 0.3.0
jupyterlab_server 2.28.0
jupyterlab_widgets 3.0.16
kiwisolver 1.4.9
lark 1.3.1
lazy_loader 0.4
llvmlite 0.46.0
markdown-it-py 4.0.0
MarkupSafe 3.0.3
matplotlib 3.10.8
matplotlib-inline 0.2.1
mdurl 0.1.2
mistune 3.2.1
mkl 2025.3.1
more-itertools 10.8.0
mpmath 1.3.0
msgpack 1.1.2
multidict 6.7.1
narwhals 2.15.0
nbclient 0.11.0
nbconvert 7.17.1
nbformat 5.10.4
nest-asyncio 1.6.0
netgen-mesher 6.2.2601.post4.dev0
netgen_occt 7.8.1
networkx 3.6.1
ngsolve 6.2.2601.post21.dev0
notebook 7.5.7
notebook_shim 0.2.4
numba 0.63.1
numpy 2.3.5
onemkl-license 2025.3.1
onnxruntime 1.23.2
orjson 3.11.7
packaging 26.0
pandas 3.0.0
pandocfilters 1.5.1
parso 0.8.5
pefile 2024.8.26
pillow 12.1.0
pip 25.3
platformdirs 4.5.1
plotly 6.5.2
pooch 1.8.2
prometheus_client 0.25.0
prompt_toolkit 3.0.52
propcache 0.4.1
proto-plus 1.27.0
protobuf 6.33.5
proxy_tools 0.1.0
psutil 7.2.2
pure_eval 0.2.3
pyasn1 0.6.2
pyasn1_modules 0.4.2
pycparser 3.0
pydantic 2.12.5
pydantic_core 2.41.5
pydub 0.25.1
Pygments 2.19.2
pyinstaller 6.18.0
pyinstaller-hooks-contrib 2026.0
PyJWT 2.10.1
PyMatting 1.1.15
pyparsing 3.3.2
pyreadline3 3.5.4
python-dateutil 2.9.0.post0
python-json-logger 4.1.0
python-multipart 0.0.21
pythonnet 3.0.5
pytz 2025.2
pyvista 0.47.1
pywebview 6.2.1
pywin32-ctypes 0.2.3
pywinpty 3.0.5
PyYAML 6.0.3
pyzmq 27.1.0
referencing 0.37.0
requests 2.32.5
rfc3339-validator 0.1.4
rfc3986-validator 0.1.1
rfc3987-syntax 1.1.0
rich 14.3.2
rich-rst 1.3.2
rpds-py 0.30.0
rsa 4.9.1
safehttpx 0.1.7
scikit-image 0.26.0
scipy 1.17.0
scooby 0.11.0
semantic-version 2.10.0
Send2Trash 2.1.0
setuptools 80.10.2
shellingham 1.5.4
six 1.17.0
sniffio 1.3.1
soupsieve 2.8.4
stack-data 0.6.3
starlette 0.50.0
sympy 1.14.0
tbb 2022.3.1
tcmlib 1.4.1
terminado 0.18.1
tifffile 2026.1.28
tinycss2 1.5.1
tomlkit 0.13.3
tornado 6.5.4
tqdm 4.67.3
traitlets 5.14.3
trame 3.13.2
trame-client 3.13.2
trame-common 1.2.4
trame-components 2.5.0
trame-plotly 3.1.0
trame-server 3.12.5
trame-vtk 2.11.12
trame-vtklocal 0.17.1
trame-vuetify 3.2.2
typer 0.21.1
typer-slim 0.21.1
typing_extensions 4.15.0
typing-inspection 0.4.2
tzdata 2025.3
umf 1.0.3
uri-template 1.3.0
urllib3 2.6.3
uvicorn 0.40.0
vtk 9.6.2
watchdog 6.0.0
wcwidth 0.5.2
webcolors 25.10.0
webencodings 0.5.1
webgui_jupyter_widgets 0.2.37
websocket-client 1.9.0
widgetsnbextension 4.0.15
wslink 2.5.7
yarl 1.22.0

[HametAl]

I created a new environment, and still I get the same error. List of packages in new environment:

aiohappyeyeballs 2.6.2
aiohttp 3.14.1
aiosignal 1.4.0
attrs 26.1.0
bottle 0.13.4
cffi 2.0.0
clr_loader 0.3.1
frozenlist 1.8.0
idna 3.18
more-itertools 11.1.0
msgpack 1.2.1
multidict 6.7.1
pip 26.1.2
propcache 0.5.2
proxy_tools 0.1.0
pycparser 3.0
pythonnet 3.1.0
pywebview 6.2.1
PyYAML 6.0.3
trame 3.13.2
trame-client 3.13.2
trame-common 1.2.4
trame-server 3.12.5
trame-vtk 2.11.12
trame-vuetify 3.2.2
typing_extensions 4.15.0
wslink 2.5.7
yarl 1.24.2

[HametAl]

I am able to make it work with using webview directly:

def showwebview(**kwargs):
    state.window[0].show()
    
server.controller.on_server_ready.add(showwebview)

DESKTOP_PORT = 8080
def start_server():
    server.start(exec_mode="main", open_browser=False,port=DESKTOP_PORT)


def on_webview_loaded():
    state.window[0].hide()
    state.window[0].load_url(f"http://localhost:{DESKTOP_PORT}")
            


if __name__ == "__main__":
    multiprocessing.freeze_support()
    state.window = [webview.create_window("Loading", background_color="#1e1e1e", easy_drag=False, frameless=True)]
    threading.Thread(target=start_server, daemon=True).start()
    webview.start(on_webview_loaded)

This method works, but has a small problem: when hovering on the vtk plotter (canvas), the plotter gets outlined

[jourdain]

Just tried the cone example from trame-vtklocal with the --app arg and it is working fine.

You will have to provide a simple example highlighting the issue, unless the file ./examples/vtk/cone.py from trame-vtklocal is not working for you. Which could mean it is an issue specific to Windows.

[HametAl]

I get the same error for ./examples/vtk/cone.py.

If I use webview directly, it works:

ready_event = threading.Event()
server_loop = None
async def start_server():
    global server_loop
    server_loop = asyncio.get_running_loop()
    task = server.start(exec_mode="task",port=0, open_browser=False, thread=True)
    await server.ready
    ready_event.set()
    await task

def run_asyncio_loop():
    asyncio.run(start_server())

def on_restored():
    state.isWinRestored = True     
    state.isWinMaximized = False     

def on_maximized():
    state.isWinMaximized = True 
    state.isWinRestored = False     
   

def on_loaded():
    hwnd = get_hwnd_by_title("myMain")
    install_workarea_clip(hwnd, rect.left, rect.top, rect.right, rect.bottom)
    webview.windows[0].maximize()
    state.isWinRestored = False     
    state.isWinMaximized = True

def on_window_closed():
    if server_loop is not None:
        asyncio.run_coroutine_threadsafe(server.stop(), server_loop)
   

if __name__ == "__main__":
    multiprocessing.freeze_support()
    threading.Thread(target=run_asyncio_loop, daemon=True).start()
    ready_event.wait()
    webviewWindow = webview.create_window(title="myMain", url=f"http://localhost:{server.port}/", easy_drag=False, frameless=True)
    webviewWindow.events.loaded += on_loaded
    webviewWindow.events.restored += on_restored
    webviewWindow.events.maximized += on_maximized
    webviewWindow.events.closed += on_window_closed
    webview.start()

But server-side and client-side renderers' sizes don't match. I used SizeObserver but didn't fix:

@state.change("view_container_size")
def view_resize(view_container_size, **kwargs):
    if not view_container_size:
        return
    size = view_container_size.get("size", {})
    wWW, wWH = size.get("width"), size.get("height")
    if wWW and wWH:
        myVtk.render_window.SetSize(int(wWW), int(wWH))
    ctx.wasm_view.update()

        with v3.VMain(scrollable=False, classes="fill-height", style="overflow:hidden; height:100%; width:100%;"):               
            with v3.VContainer(v_show=("active_view == '3D_h'"), classes="ma-0 pa-0 fill-height overflow-hidden"):
                with v3.VCol(style='height:100%;', classes="ma-0 pa-0", tile=True):
                    with v3.VRow(style='height:8%;', classes="ma-0 pa-0", tile=True):
                        v3.VTextField(v_model=("cmd_input",), v_on_keydown_enter_prevent=(generate_geo_points,), input=(validate_input, "[$event]"), disabled=("cmdIsDisabled",),error_messages=("input_errors",[]), density="compact", autofocus=True, tile=True)
                    with v3.VRow(style='height:92%;', classes="ma-0 pa-0", tile=True):
                        with client.SizeObserver("view_container_size", style="height:100%; width:100%;"):                   
                            with vtklocal.LocalView(csatVtk.render_window, throttle_rate=20, ctx_name="wasm_view") as view:

If I don't use sizeobserver, and instead, just restore the window size using the window buttons, client and server side renderers' sizes match.