Button should be disabled in QtSDKInstaller.

Steps:
1. Open install package.
2. Double Click"Qt SDK Installer.app"
3. Select "Customer",Click "Contiue"
4. Click"Select All" button

Excepted result:
After select all ,this button should be disabled.Same as the "Default" button
"deselect all " button should be the same.

Actually result:.
Click select all again ,there is no any response.