I'm running GUI application in Docker using xrdp.

I can connect to rdp server (using xrdp), and interact with application.

Now I need to rung GUI application in different resolution. When I connect with geometry parameter xfreerdp /size:1680x970 the RDP window has the desired size, but the running application remains the same size (small).

I tried connecting to the running container and changing the resolution using xrandr, but xrandr reports the correct (larger) resolution.

Ny question is: how can I tell the application (Java) to run in fullscreen mode or accept the new resolution?

I simulate this problem by running xclock - small clock but large window:

I know that in the case of xclock I can solve the issue by adding the -geometry parameter, but that's not what I want.

Here is the testing Dockerfile:

FROM ubuntu:latest
ENV DEBIAN_FRONTEND=noninteractive
RUN apt update && apt install -y xdg-utils xrdp x11vnc
RUN useradd -m -s /bin/bash pou
RUN echo 'pou:pou' | chpasswd
RUN echo "#!/bin/sh\nxclock " > /etc/xrdp/startwm.sh &&  chmod +x /etc/xrdp/startwm.sh
CMD service xrdp stop && service xrdp start && tail -F /var/log/xrdp.log

How to define application size, or run application in fullscreen mode?

Thank you