If your macOS app is a SwiftUI app with custom button styles that targets macOS 15+, you don’t need my click-through fix anymore. Reported via Feedback Assistant on 2024-04-11, FB13720950 is now closed because macOS 15 Beta 2 solved the issue.
On macOS, there’s 1 active window that receives your key input. Then there’s all the other windows, which are potentially invisible or obstructed by other windows. These inactive windows can be brought to the front and made active with a click. Then you can interact with these windows like normal. With inactive but visible windows, you cannot select items from lists, for example. The UI reflects this with a greyed-out or dimmed representation. You need to click once to activate the window (on the surface of the window, so to speak), then another time to interact with the control.
This is how I made dark NSButton with the NSButton.BezelStyle.recessed display legible light text on dark background with macOS Mojave an up. Recently, a user of The Archive pointed out that the in-app guide doesn’t display properly with a light system appearance. In dark mode, you wouldn’t notice the problem, but in light mode, the button colors rendered them illegible. Only when you press a button does its text light up properly for its background color. Have a look: