reduce-window does not work

[dstc]

Good evening,

when i open a file, on the top right of the window you have - + x ;
x is to close the window
+ is to put full screen or small size
- should be to put the file standby with a icon on the bottom bar, but here with me when i clic on this minus the file disappear completely without to ask for saving, and you loos all work done on it since latest saving.

How can i solve this problem

[all41]

This sounds like you are using Mate
Try this:
Right click on the menu and select 'Add to Panel'
scroll down to the Window List, and click 'Add'