fix(VTreeview): prevent checkbox deselection when mandatory

fixes #21614

Author: KaelWD

packages/vuetify/src/components/VTreeview/VTreeviewChildren.tsx

@@ -8,7 +8,7 @@ import { makeDensityProps } from '@/composables/density'
 import { IconValue } from '@/composables/icons'
 
 // Utilities
-import { computed, reactive, toRaw, withModifiers } from 'vue'
+import { computed, reactive, toRaw } from 'vue'
 import { genericComponent, propsFactory } from '@/util'
 
 // Types
@@ -92,7 +92,7 @@ export const VTreeviewChildren = genericComponent<new <T extends InternalListIte
 
     function selectItem (select: (value: boolean) => void, isSelected: boolean) {
       if (props.selectable) {
-        select(!isSelected)
+        select(isSelected)
       }
     }
 
@@ -124,7 +124,8 @@ export const VTreeviewChildren = genericComponent<new <T extends InternalListIte
                   indeterminateIcon={ props.indeterminateIcon }
                   falseIcon={ props.falseIcon }
                   trueIcon={ props.trueIcon }
-                  onClick={ withModifiers(() => selectItem(slotProps.select, slotProps.isSelected), ['stop']) }
+                  onUpdate:modelValue={ v => selectItem(slotProps.select, v) }
+                  onClick={ (e: PointerEvent) => e.stopPropagation() }
                   onKeydown={ (e: KeyboardEvent) => {
                     if (!['Enter', 'Space'].includes(e.key)) return
                     e.stopPropagation()

packages/vuetify/src/components/VTreeview/VTreeviewItem.tsx

@@ -91,27 +91,25 @@ export const VTreeviewItem = genericComponent<VListItemSlots>()({
             prepend: hasPrepend ? slotProps => {
               return (
                 <>
-                  <VListItemAction start={ false }>
+                  <VListItemAction start>
                     { props.toggleIcon ? (
-                        <VBtn
-                          density="compact"
-                          icon={ props.toggleIcon }
-                          loading={ props.loading }
-                          variant="text"
-                          onClick={ onClickAction }
-                        >
-                          {{
-                            loader () {
-                              return (
-                                <VProgressCircular
-                                  indeterminate="disable-shrink"
-                                  size="20"
-                                  width="2"
-                                />
-                              )
-                            },
-                          }}
-                        </VBtn>
+                      <VBtn
+                        density="compact"
+                        icon={ props.toggleIcon }
+                        loading={ props.loading }
+                        variant="text"
+                        onClick={ onClickAction }
+                      >
+                        {{
+                          loader: () => (
+                            <VProgressCircular
+                              indeterminate="disable-shrink"
+                              size="20"
+                              width="2"
+                            />
+                          ),
+                        }}
+                      </VBtn>
                     ) : (
                       <div class="v-treeview-item__level" />
                     )}