finished implementing setting category

gui/ui/state.slint

@@ -4,9 +4,7 @@ export struct SItem {
     amount: int,
 }
 
-export struct SButtonItem{
-    name: string,
-    category: string}
+export struct SButtonItem { name: string, category: string }
 
 export global State {
     in-out property <[SItem]> list: [
@@ -20,6 +18,7 @@ export global State {
     callback delete-checked();
     callback inc-amount(string);
     callback dec-amount(string);
+    callback set-cat(string, string);
     in-out property <string> server-address;
     in property <[SButtonItem]> favorites: [
         { name: "mjölk", category: "kyl" },