In the Classic days, if you wanted to use a window that wasn't frontmost, you could click anywhere on it to bring it to the front.Mac OS X introduced a feature called "click-through" where certain controls, like the "traffic-light" buttons in the window title, would work even for background windows. Applications can also make other controls, or even the entire window, work with click-through. To make things a little confusing, in older versions, click-through was off by default for Carbon apps, but on by default for Cocoa apps.

Some people (including myself) never got used to click-through; if you too wish to have more control over what happens when you click on a background window, Klicko may solve your problem.

Klicko is a simple Cocoa application. It doesn't hack the system, other applications, inject code or do anything magic. You can run it in the Dock or in the menu bar. See below for details. Version 1.0.1 (Size: 148590 bytes) is for Mac OS X 10.5 (Leopard) and up, for both PowerPC and Intel.

Klicko is freeware. However, if you think it was useful to you, you may contribute with a donation.

Klicko is currently localized into English, Portuguese (Brazilian), French (by Ronald Leroux), German (with the help of M. Uli Kusterer) and Italian (by Andrea Gelati). Please contact me if you're interesting in doing some other language (Japanese and Spanish would be welcome).

Here's the Klicko preferences window:

The popup menu in the window title is important. If it's set to "Excluded Applications", all windows belonging to the applications listed in the window will get click-throughs; if it's set to "Included Applications", only those applications won't get click-throughs. That is, the popup changes the nature of the application list.

You can add any running application by clicking on the "+" button; a pop-up menu will appear. You can also drag applications (running or not) from the Finder into (and out of) the window, of course. (If you have several copies of an application installed, putting one of them in will work for all.)

Beyond that, at any time you can direct any click to a background window by holding down any modifier key. Some applications don't use standard windows or use them in a way that Klicko can't activate properly; if you find that clicking on a window has no effect at all, hold down a modifier key and try again.

Klicko relies on the Accessibility interface, which usually must be turned on in the System Preferences. If you'd rather not do that, you can authorize Klicko to ask for an administrator password, and from then on work without that option (Klicko has to be in the main /Application folder for this to work). Some applications may not implement Accessibility in a way that Klicko understands. Please use the exclusion list in such a case.

Note that there's no way to disable the highlighting of the window "traffic light" buttons, so, to minimize user confusion Klicko always allows click-through on those buttons. Klicko will also always pass through clicks on windows belonging to background or full-screen applications, to dialogs, palettes, and similar interface elements, and to the Finder desktop.

Code Signing: Klicko is codesigned for extra security. Basically, this means that you can verify if the application's executable has been signed by a specific developer, and that you can have some assurance that code or resources have not been tampered with by third parties.
To check that Klicko's signature is intact, open Terminal, paste in the following command, and press the Return key:

(assuming that you installed Klicko in the main /Applications folder.) You should see several result lines in the Terminal. Authority=Rainer Brockerhoff should be present, and identify the author. The last line should end with ...root = H"4cbb97c74336f7ee6aa566122a5e7688e1c725dc" and uniquely identify the author's signature. Now run the following command:

If the application is intact, this should display valid on disk; otherwise you'll see code or signature modified. In the latter case, the application will not run when double-clicked.

Release Notes: Version 1.0.1 (123)

Release Notes: Version 1.0.1 (120)

Release Notes: Version 1.0.1 (119)

Release Notes: Version 1.0.1 (113)

Release Notes: Version 1.0.1 (109)

Release Notes: Version 1.0.1 (103)

Release Notes: Version 1.0.1 (97)

Release Notes: Version 1.0 (87)

Release Notes: Version 1.0 (79)

Release Notes: Version 1.0 (73)

Release Notes: Version 1.0 (71)

Release Notes: Version 1.0 (67)