add option to center the modal

src/components/dialog_modal/dialog_modal.js

@@ -8,6 +8,11 @@ const DialogModal = {
       default: () => {},
       type: Function
     }
+  },
+  computed: {
+    mobileCenter () {
+      return this.$store.getters.mergedConfig.modalMobileCenter
+    }
   }
 }
 

src/components/dialog_modal/dialog_modal.vue

@@ -1,7 +1,7 @@
 <template>
   <span
     class="dialog-container"
-    :class="{ 'dark-overlay': darkOverlay }"
+    :class="{ 'dark-overlay': darkOverlay, '-center-mobile': mobileCenter }"
     @click.self.stop="onCancel()"
   >
     <div
@@ -100,6 +100,10 @@
     justify-content: stretch;
     align-items: end;
     justify-items: stretch;
+
+    &.-center-mobile {
+      align-items: center;
+    }
   }
 
   .dialog-modal.panel {

src/components/settings_modal/tabs/appearance_tab.vue

@@ -345,6 +345,11 @@
     <div class="setting-item">
       <h2>{{ $t('settings.visual_tweaks') }}</h2>
       <ul class="setting-list">
+        <li>
+          <BooleanSetting path="modalMobileCenter">
+            {{ $t('settings.mobile_center_dialog') }}
+          </BooleanSetting>
+        </li>
         <li>
           <ChoiceSetting
             id="forcedRoundness"