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.

Some improvements are needed, like the GUI not displaying the flutter executable when browsing for it (thus requiring manually typing the name). Please feel free to submit a PR if it can be solved. 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.