Click-through is one of the things which differs macOS from other OSs. In two words, in macOS clicking on a background window (which doesn’t have focus) only makes it active, without passing the click to the window itself. So you don’t accidentally make unwanted action inside the app while just trying to bring the app to foreground.
Although all other apps in macOS has it disabled, currently, ST3 window has ‘click-though’ feature enabled, which is against Apple guidelines:
Avoid providing click-through for an item or action whose result might be dangerous or undesirable. Specifically, avoid enabling click-through for an item that:
- Performs a potentially harmful action that users can’t cancel (for example, the Delete button in Mail)
- Performs an action that is difficult or impossible to cancel (such as the Send button in Mail)
- Dismisses a dialog without telling the user what action was taken (for example, the Save button in a Save dialog that overwrites an existing file and automatically dismisses the dialog)
- Removes the user from the current context (for example, selecting a new item in a Finder column that changes the target of the Finder window)
Last point is exactly my case, as ST3 while being in background only has it’s sidebar visible, so switching from Safari to ST3 only possible by clicking files/folders in ST3 sidebar, which changes currently opened file in ST3 (= switches context).
No other apps do that, they all require two clicks to perform an action when the app was in background.
Here is one poor guy asking for the same, but on windows: https://forum.sublimetext.com/t/focus-on-click-in-windows/12575