Hi, thanks for your answer.
It is kind of sci-fi, I have reinstalled OS X, just for fun :-( , no change. I will investigate yet. It irritates me. I don't know about anything of such nature (monitoring clicks). Better Touch Tool I have installed and I am trying now but only after your message and btw thanks for the tip :-).
If anybody has any idea, it would be great. Thanks!
I have here installed these apps:
Alfred 3.app Mission Control.app
App Store.app Notes.app
Automator.app Photo Booth.app
BetterTouchTool.app Photos.app
Calculator.app Postgres.app
Calendar.app Preview.app
Chess.app QuickTime Player.app
Contacts.app Reminders.app
DVD Player.app Remote Desktop Connection.app
Dashboard.app Safari.app
Dictionary.app Siri.app
FaceTime.app Slack.app
Font Book.app Spotify.app
Google Chrome.app Stickies.app
HipChat.app Sublime Text 2.app
Image Capture.app SyncAnybarPorts.app
IntelliJ IDEA.app System Preferences.app
Launchpad.app TextEdit.app
Mail.app Time Machine.app
Maps.app Utilities
Messages.app VirtualBox.app
Microsoft Messenger.app iBooks.app
Microsoft Office 2011 iTunes.app
Microsoft Remote Desktop.app
Activity Monitor.app Grab.app
AirPort Utility.app Grapher.app
Audio MIDI Setup.app Keychain Access.app
Bluetooth File Exchange.app Migration Assistant.app
Boot Camp Assistant.app Script Editor.app
ColorSync Utility.app System Information.app
Console.app Terminal.app
Digital Color Meter.app VoiceOver Utility.app
Disk Utility.app