Confusing tabview in dark mode
In the dark theme, the colors for the inactive tab in the header bar comes out to #262626, which is extremely close to the window background of #242424. This makes it confusing as to which tab is active, since in older UI designs it's common for the active tab to connect with the rest of the window. Even more confusingly, when the window is not in focus, the active tab does actually match the window background.
This is not an issue in the light theme, where color for the active tab is closer to the window color than the color for inactive tabs.