>>1. In one website how many places I can use this thumb nail is there any limit or restriction.
Unlimited.
2. Can I edit the Thumbnail size or it is fixed? If can be changed where and how pls explain?
Yes.
Please check the following property:
Gallery.MaxThumbHeight Property
The maximum height of the thumbnails. Default is 100.
Gallery.MaxThumbWidth Property
The maximum width of the thumbnails. Default is 100.
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