The ImGuiMenu class currently constraints the width to a hardcoded value, and also enables auto-resizing. Both of these settings overlap, in that they both prevent the user from resizing the ImGui menu, but the width constraint effectively overrides the auto-resizing feature, which sets the width at a potentially undesirable value (e.g., wide content can be truncated). Removing the width constraint and just letting ImGui resize the menu automatically seems to be a good approach. I've only tested this on some code in a private repo that I don't want to share publicly, but I am happy to write up a simple example demonstrating the change, or discuss an alternative approach (e.g., perhaps a user might want to set a maximum width constraint or manually fix the width on their end).

Checklist

• All changes meet libigl style-guidelines.
• Adds new .cpp file.
• Adds corresponding unit test.
• This is a minor change.