Bug 789633

Description of problem:
I have the flatbed-scanner "Epson Perfection V300".
lsusb:
Bus 001 Device 008: ID 04b8:0131 Seiko Epson Corp. Perfection V300

I use Gnome3 but my favorite scan-app is the KDE-App "scangui" (the german name "Bilder scannen"). But after I used that and closed that I can't turn of the scanner. To turn off I must press a button on the scanner for 3 secs and then it must be turn off, but it didn't. So I think after closing the "scangui" the usb-connection still remains and so the scanner doesn't turn off.
All other scan-apps doesn't show that problem. After these scan-apps I can turn off the scanner.
So I have two choices:
1. disconnect the usb-cable and turn the scanner off
or
2. start afterwards another scan-app and close them, so then I can turn off the scanner

Version-Release number of selected component (if applicable):
Fedora 16 (64 Bit), Gnome 3.2.1, KDE "scangui" 2.5.0 (KDE 4.7.4) doesn't work, scanner-driver "iscan.x86_64 2.28.0-2.ltdl7"
Scan-Apps that handle the situation correct: xsane frontend 0.998, "Image Scan!" 2.28 (iscan) from Epson, 

How reproducible:
every time

Steps to Reproduce:
1. turn on scanner "Epson Perfection V300"
2. start KDE "scangui"
3. close KDE "scangui"
4. try to turn off the scanner with the scanner-powerbutton 3 secs pressed
  
Actual results:
scanner remains on

Expected results:
scanner turn off

Additional info:
If I start KDE "scangui" before the scanner is turned on a dialog appears, that no scanner is found. And then I turn on the scanner, I press the scangui-button "reload devicelist" (in german "Geräteliste neu laden") the app doesn't make a full new scan and so it doesn't find the scanner. I have to close "scangui" and restart it while the scanner is already turned on.