Hi,
When I upload/delete a file in the panel and do not save my changes before to the page, all changes are lost !? Thats no good 
When working with for example, a structure/builder field, and after a while, hmm I need a image to my page, and upload one, all the work you done are gone… Because you don´t want to save your changes before you are ready… You want to keep creating…
This should not happen at all. Kirby saves changes in the session, so your changes should still be there even if you upload stuff or changes pages.
What Kirby version are you using?
Sorry, my bad!
Forgotten about some hooks that triggered “page update” on file upload… 