I took me a while to figure this is out, but I finally did. When ccleaner is minimized to the system tray, it constantly (every 30s or so) steals the focus, so that -for example- I can not scroll a web page or type anything, because the input is not directed to the browser anymore.
For example, watching a video on youtube in full screen, after a while, i can not return to normal mode by pressinng ESC, it doesn't work, i have to click on the image to get the focus back to the browser and then i can press ESC.
Same thing happens when watcching a video, after a few seconds the mouse wheel stops responding and I have to click somewhere in the page to get the focus back.
I tried a million things until I closed the systray icon: immediately fixed the issue.
this is EXTREMELY ANNOYING and it disrupts whatever I'm doing every 30s or so.
and it's not only the browser. For example, I open the task manager and after a few seconds, i can not scroll through the list of running processes with the mouse wheel, because ccleaner stole the focus.
and so on...
Edit: It also happens while minimized to the taskbar, you can phisycally see the focus go to ccleaner (the ccleaner taskbar icon gets hilighted by itself)
I'm thinking that it was probably related to yesterdays licence server overload?
It may have been that the updated CCleaner was trying to check the licence information, but because of the server issue was unable to complete the check and authenticate the key.
So if CCleaner was left running (ie. Smart Cleaning, Automatic Updates, minimised) it was periodically trying to check the licence again, and stealing focus whilst it did that.
In which case closing and reopening CCleaner would/should have completed the check and cleared it.
@jvidalis your CCleaner still stealing focus today?
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I'm thinking that it was probably related to yesterdays licence server overload?
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Updated to CC5.84 last night and didn't see anything untoward happening with focus stealing - or this morning. Although by that time the server load was a bit more reasonable. Can you remember the time of day you were seeing it jumping?
Your conclusion about licence check retries seems logical - though it should not be taking focus when it does so (in theory). We'll keep an eye on this - we're currently working to make CCleaner less intrusive - not more so.
@jvidallet's see if we can track down just what is causing this for you.
At the moment you are the only one reporting this problem, and so the more details we can get from you the better we may be able to work out what is happening.
First the general questions:
What version of Windows are you using, if it's Windows 10 then which build? (eg. 1909, 20H1, 20H2, 21H1, 21H2).
What antivirus are you using, if it's not Defender then which version of your antivirus?
For CCleaner:
Are you using CCleaner Free or Pro version?
Do you use Health Check or Custom Clean?
Do you have Smart Ceaning turned on? If so then what are the settings? (A screenshot would help).
What are your settings in Options>Updates?
I think programs stealing focus is a Windows "feature", well not really a liked thing. And even if you or someone was running Windows 10 it can and will steal focus at times.