The TileSet dialog is a properties page used to allow a resource to be used as a tileset even when it is not backed onto a WMS-C tile cache.
Related tasks
Enabling a Tileset from a WMS Server
Check this checkbox to enable using tilesets for this resource. By pressing this a set of default scales will be provided - these are taken from the viewport scales.
The width and height of the tiles - default is 265
The type of image expected from the WMS server
The scales need to be specified for the tileset - WMS-C, you can add more if you know the scales your tileset will work at. These will be used to calculate resolutions for the TileSet.