Size of full backup not changing after injection?

[cke]

Hey,
please help me understand. I have a forever forward backup. My understanding was that incremental backups get injected into the full backup. However the size of the file never changes (not in the Backup properties and not in Windows Explorer).
Is this as intended? Are there some kind of reserved blocks in the vbk that just get filled? Here is an example screenshot with shots taken two days in a row and it looks as if there was just one file deleted and one file added.

[foggy]

Chris, this could mean that no essentially new blocks were backed up during the corresponding incremental job run, so all the blocks from the increment have replaced their previous "versions" stored in the full backup. Another point to consider is that once the block is deleted, it is not physically removed but just marked as free and can be subsequently reused by other data.

[veremin]

If you feel worrisome about the oldest restore point, there is no preventing you from performing test restore to confirm its recoverability. Thanks.