Why can't I see tabs?

By default, tabs are configured to only show up when the scene view is maximized. You can maximize the scene view by pressing Shift+Tab with the window focused, or by double-clicking it. You can also change your Peek preferences to always show the tabs, even when the scene view is minimized.

How can I resize tabs?

Right-click a tab to open it as a pinned window. This will let you move and resize it. When closed, the tab will remember its size even if opened as a popup.

Is Peek compatible with ProBuilder?

Yes, but the Peek shortcuts to navigate the scene toolbar, Alt+[0-9], conflict with ProBuilder's shortcuts to assign a material from the material palette. Starting in Unity 2019, you can use the shortcut remapper to resolve the conflict.

In Unity 2018, you can comment the line #define ENABLE_PRIMARY_SHORTCUTS in ShortcutsIntegration.cs to disable the Peek shortcuts and give priority to ProBuilder. Unfortunately, because ProBuilder is distributed as a package, you cannot edit it to disable its shortcuts and give priority to Peek.

Is Peek compatible with Odin Inspector?

Yes!