When the window is big enough, the sidebar should be pinned open

[fitojb]

It's annoying to have to repeatedly open the sidebar each time I want to change modes. Save me a click and take advantage of the extra screen estate when maximized!

[MicrosoftIssueBot]

This is your friendly Microsoft Issue Bot. I've seen this issue come in and have gone to tell a human about it.

[jaigak]

Instead of just maximized, there could be a snap point in which the sidebar is automatically opened and pinned.

[mdtauk]

This is standard common behaviour for UWP apps using NavigationView, but Calculator is more A-typical by using the collapsed overlay mode, because of the common option for keeping the window small.

But when the window is larger, it makes sense to keep it visible.