Tool for easily creating an AppImage on Linux for a Flutter app

When I created my Simple Notes Android app, I not only created APK files for it, I also built it to run on Linux. So it ended up having an executable file which would not run unless there were some extra supporting folders. This was messy, and I wanted a single file. I found that creating an AppImage was a good way to do this. There are a bunch of developer tools for the purpose. I chose the appimage tool to convert app directories to appImages.

Downloaded the appimagetool-x86_64.AppImage file from here. 

Made it executable: 

chmod +x appimagetool-x86_64.AppImage 

You can see available options via:

./appimagetool-x86_64.AppImage --help 

Get your application files into a folder. In my case I had to create a `simple_notes` folder and pasted the `simple_notes` linux executable and the `lib` and `data` folders there. I also copied a `note.png` application icon for my Simple Notes application to have a unique icon. In the `simple_notes` folder I also had to create a `SimpleNotes.desktop` file containing:

[Desktop Entry]
Type=Application
Name=Simple Notes 3
Exec=simple_notes
Icon=note
Categories=Utility;

But it showed errors like .

So I simply asked Grok to create a Python program which can automatically create the AppImage for me. It worked flawlessly. The code is here.

I know the GUI does not look too good and has a few flaws like not displaying the flutter executable when browsing for it (thus requiring manually typing the name), but it was not something that I wanted to spend more time on for now. My SimpleNotes AppImage was built and it works on typing ./SimpleNotes.AppImage. 

I wonder why the AppImage team did not create this kind of a simple way of building an AppImage.