1. Launch Steam.
2. During message "Connecting to Steam account...", switch to some other application.
3. When connecting to Steam will be completed and main window will show, Steam will make main window active. OK, makes sense.
4. Switch to other application again. After about 5 seconds, Steam will activate its main window again, without any reason.

My window manager is Unity.

Processor Information:
    Vendor:  AuthenticAMD
    Speed: 2300 Mhz
    2 logical processors
    2 physical processors
    HyperThreading:  Unsupported
    FCMOV:  Supported
    SSE2:  Supported
    SSE3:  Supported
    SSSE3:  Supported
    SSE4a:  Supported
    SSE41:  Unsupported
    SSE42:  Unsupported

Network Information:
    Network Speed:  

Operating System Version:
    Ubuntu 12.04.1 LTS (64 bit)
    Kernel Name:  Linux
    Kernel Version:  3.2.0-36-generic
    X Server vendor:  The X.Org Foundation
    X Server release:  11103000

Video Card:
    Driver:  ATI Technologies Inc. AMD Radeon HD 6570M/5700 Series

    Driver Version:  4.2.12002 Compatibility Profile Context 9.012
    Desktop Color Depth: 24 bits per pixel
    Monitor Refresh Rate: 59 Hz
    VendorID:  0x1002
    DeviceID:  0x68c0
    Number of Monitors:  1
    Number of Logical Video Cards:  1
    Primary Display Resolution:  1366 x 768
    Desktop Resolution: 1366 x 768
    Primary Display Size: 13,54" x 7,60"  (15,51" diag)
                                            34,4cm x 19,3cm  (39,4cm diag)
    Primary VRAM Not Detected

Sound card:
    Audio device: 

Memory:
    RAM:  2945 Mb

Miscellaneous:
    UI Language:  English
    LANG:  ru_UA.UTF-8
    Microphone:  Not set
    Total Hard Disk Space Available:  297340 Mb
    Largest Free Hard Disk Block:  226711 Mb

Installed software:

Recent Failure Reports: