diff --git a/app/controllers/post_appeals_controller.rb b/app/controllers/post_appeals_controller.rb
index 18a14494b..116c94030 100644
--- a/app/controllers/post_appeals_controller.rb
+++ b/app/controllers/post_appeals_controller.rb
@@ -3,7 +3,7 @@ class PostAppealsController < ApplicationController
   respond_to :html, :xml, :json, :js
 
   def new
-    @post_appeal = PostAppeal.new
+    @post_appeal = PostAppeal.new(post_appeal_params)
     respond_with(@post_appeal)
   end
 
diff --git a/app/controllers/post_flags_controller.rb b/app/controllers/post_flags_controller.rb
index b80bad83b..b64a729e5 100644
--- a/app/controllers/post_flags_controller.rb
+++ b/app/controllers/post_flags_controller.rb
@@ -3,7 +3,7 @@ class PostFlagsController < ApplicationController
   respond_to :html, :xml, :json, :js
 
   def new
-    @post_flag = PostFlag.new
+    @post_flag = PostFlag.new(post_flag_params)
     respond_with(@post_flag)
   end
 
diff --git a/app/controllers/post_replacements_controller.rb b/app/controllers/post_replacements_controller.rb
index c83fd7c8b..8327b2a5e 100644
--- a/app/controllers/post_replacements_controller.rb
+++ b/app/controllers/post_replacements_controller.rb
@@ -1,9 +1,10 @@
 class PostReplacementsController < ApplicationController
-  respond_to :html, :xml, :json
+  respond_to :html, :xml, :json, :js
   before_action :moderator_only, except: [:index]
 
   def new
-    @post = Post.find(params[:post_id])
+    @post_replacement = Post.find(params[:post_id]).replacements.new
+    respond_with(@post_replacement)
   end
 
   def create
diff --git a/app/controllers/posts_controller.rb b/app/controllers/posts_controller.rb
index 01ef84c76..3e9fd8e62 100644
--- a/app/controllers/posts_controller.rb
+++ b/app/controllers/posts_controller.rb
@@ -23,9 +23,7 @@ class PostsController < ApplicationController
 
   def show
     @post = Post.find(params[:id])
-    @post_flag = PostFlag.new(:post_id => @post.id)
-    @post_appeal = PostAppeal.new(:post_id => @post.id)
-    
+
     include_deleted = @post.is_deleted? || (@post.parent_id.present? && @post.parent.is_deleted?) || CurrentUser.user.show_deleted_children?
     @parent_post_set = PostSets::PostRelationship.new(@post.parent_id, :include_deleted => include_deleted)
     @children_post_set = PostSets::PostRelationship.new(@post.id, :include_deleted => include_deleted)
diff --git a/app/javascript/src/javascripts/post_appeals.js b/app/javascript/src/javascripts/post_appeals.js
deleted file mode 100644
index 814c18343..000000000
--- a/app/javascript/src/javascripts/post_appeals.js
+++ /dev/null
@@ -1,35 +0,0 @@
-let PostAppeal = {};
-
-PostAppeal.initialize_all = function() {
-  if ($("#c-posts").length && $("#a-show").length) {
-    this.initialize_appeal();
-  }
-}
-
-PostAppeal.initialize_appeal = function() {
-  $("#appeal-dialog").dialog({
-    autoOpen: false,
-    width: 700,
-    modal: true,
-    buttons: {
-      "Submit": function() {
-        $("#appeal-dialog form").submit();
-        $(this).dialog("close");
-      },
-      "Cancel": function() {
-        $(this).dialog("close");
-      }
-    }
-  });
-
-  $("#appeal").on("click.danbooru", function(e) {
-    e.preventDefault();
-    $("#appeal-dialog").dialog("open");
-  });
-}
-
-$(document).ready(function() {
-  PostAppeal.initialize_all();
-});
-
-export default PostAppeal
diff --git a/app/javascript/src/javascripts/post_flags.js b/app/javascript/src/javascripts/post_flags.js
deleted file mode 100644
index 27f4d56d3..000000000
--- a/app/javascript/src/javascripts/post_flags.js
+++ /dev/null
@@ -1,39 +0,0 @@
-let PostFlag = {};
-
-PostFlag.initialize_all = function() {
-  if ($("#c-posts").length && $("#a-show").length) {
-    this.initialize_flag();
-  }
-}
-
-PostFlag.initialize_flag = function() {
-  $("#flag-dialog").dialog({
-    autoOpen: false,
-    width: 700,
-    modal: true,
-    buttons: {
-      "Submit": function() {
-        $("#flag-dialog form").submit();
-        $(this).dialog("close");
-      },
-      "Cancel": function() {
-        $(this).dialog("close");
-      }
-    }
-  });
-
-  $('#flag-dialog form').submit(function() {
-    $('#flag-dialog').dialog('close');
-  });
-
-  $("#flag").on("click.danbooru", function(e) {
-    e.preventDefault();
-    $("#flag-dialog").dialog("open");
-  });
-}
-
-$(function() {
-  PostFlag.initialize_all();
-});
-
-export default PostFlag
diff --git a/app/javascript/src/javascripts/posts.js.erb b/app/javascript/src/javascripts/posts.js.erb
index 9a1eb4b96..795c23e87 100644
--- a/app/javascript/src/javascripts/posts.js.erb
+++ b/app/javascript/src/javascripts/posts.js.erb
@@ -31,7 +31,6 @@ Post.initialize_all = function() {
     this.initialize_post_image_resize_links();
     this.initialize_post_image_resize_to_window_link();
     this.initialize_similar();
-    this.initialize_replace_image_dialog();
     this.initialize_gestures();
 
     if ((Utility.meta("always-resize-images") === "true") || (Utility.meta("viewport") && (window.screen.width <= 660))) {
@@ -616,32 +615,6 @@ Post.initialize_saved_searches = function() {
   });
 }
 
-Post.initialize_replace_image_dialog = function() {
-  $("#replace-image-dialog").dialog({
-    autoOpen: false,
-    width: 700,
-    modal: true,
-    buttons: {
-      "Submit": function() {
-        $("#replace-image-dialog form").submit();
-        $(this).dialog("close");
-      },
-      "Cancel": function() {
-        $(this).dialog("close");
-      }
-    }
-  });
-
-  $('#replace-image-dialog form').submit(function() {
-    $('#replace-image-dialog').dialog('close');
-  });
-
-  $("#replace-image").on("click.danbooru", function(e) {
-    e.preventDefault();
-    $("#replace-image-dialog").dialog("open");
-  });
-};
-
 $(document).ready(function() {
   Post.initialize_all();
 });
diff --git a/app/javascript/src/javascripts/utility.js b/app/javascript/src/javascripts/utility.js
index 35ade85ec..802855e17 100644
--- a/app/javascript/src/javascripts/utility.js
+++ b/app/javascript/src/javascripts/utility.js
@@ -36,6 +36,31 @@ Utility.error = function(msg) {
   }
 }
 
+Utility.dialog = function(title, html) {
+  const $dialog = $(html).dialog({
+    title: title,
+    width: 700,
+    modal: true,
+    close: function() {
+      // Defer removing the dialog to avoid detaching the <form> tag before the
+      // form is submitted (which would prevent the submission from going through).
+      $(() => $dialog.dialog("destroy"));
+    },
+    buttons: {
+      "Submit": function() {
+        $dialog.find("form").submit();
+      },
+      "Cancel": function() {
+        $dialog.dialog("close");
+      }
+    }
+  });
+
+  $dialog.find("form").on("submit.danbooru", function() {
+    $dialog.dialog("close");
+  });
+}
+
 Utility.keydown = function(keys, namespace, handler) {
   if (Utility.meta("enable-js-navigation") === "true") {
     $(document).on("keydown.danbooru." + namespace, null, keys, handler);
diff --git a/app/views/artist_commentaries/_form.html.erb b/app/views/artist_commentaries/_form.html.erb
index 537e42b1a..dee5c5a0a 100644
--- a/app/views/artist_commentaries/_form.html.erb
+++ b/app/views/artist_commentaries/_form.html.erb
@@ -5,7 +5,7 @@
     <label>Copy from</label>
     <%= select_tag :commentary_source_type, options_for_select(%w[Source Post]) %>
     <%= text_field_tag :commentary_source, post.source %>
-    <%= text_field_tag :commentary_post_id, (post.parent.try(&:id) || post.children.first.try(&:id)), :style => "display: none;" %>
+    <%= text_field_tag :commentary_post_id, post.parent_id, :style => "display: none;" %>
     <%= button_tag "Fetch" %>
   </div>
 </form>
diff --git a/app/views/post_appeals/_new.html.erb b/app/views/post_appeals/_new.html.erb
index c06e3705f..b652c1d08 100644
--- a/app/views/post_appeals/_new.html.erb
+++ b/app/views/post_appeals/_new.html.erb
@@ -1,9 +1,13 @@
-<%= format_text(WikiPage.titled(Danbooru.config.appeal_notice_wiki_page).first.try(&:body)) %>
+<div class="appeal-dialog-body">
+  <div class="prose">
+    <%= format_text(WikiPage.titled(Danbooru.config.appeal_notice_wiki_page).first.try(&:body)) %>
+  </div>
 
-<%# XXX dtext_field expects there to be a `post_appeal` instance variable. %>
-<% @post_appeal = post_appeal %>
-<%= simple_form_for(@post_appeal, format: :js, remote: true) do |f| %>
-  <%= f.hidden_field :post_id %>
-  <%= dtext_field "post_appeal", "reason", preview_id: "dtext-preview-for-post-appeal" %>
-  <%= dtext_preview_button "post_appeal", "reason", preview_id: "dtext-preview-for-post-appeal" %>
-<% end %>
+  <%# XXX dtext_field expects there to be a `post_appeal` instance variable. %>
+  <% @post_appeal = post_appeal %>
+  <%= simple_form_for(@post_appeal, format: :js, remote: true) do |f| %>
+    <%= f.hidden_field :post_id %>
+    <%= dtext_field "post_appeal", "reason", preview_id: "dtext-preview-for-post-appeal", type: "string" %>
+    <%= dtext_preview_button "post_appeal", "reason", preview_id: "dtext-preview-for-post-appeal" %>
+  <% end %>
+</div>
diff --git a/app/views/post_appeals/new.js.erb b/app/views/post_appeals/new.js.erb
new file mode 100644
index 000000000..f03b42d35
--- /dev/null
+++ b/app/views/post_appeals/new.js.erb
@@ -0,0 +1 @@
+Danbooru.Utility.dialog("Appeal post", "<%= j render "post_appeals/new", post_appeal: @post_appeal %>");
diff --git a/app/views/post_flags/_new.html.erb b/app/views/post_flags/_new.html.erb
index da735b3b7..280be9949 100644
--- a/app/views/post_flags/_new.html.erb
+++ b/app/views/post_flags/_new.html.erb
@@ -1,9 +1,13 @@
-<%= format_text(WikiPage.titled(Danbooru.config.flag_notice_wiki_page).first.try(&:body)) %>
+<div class="flag-dialog-body">
+  <div class="prose">
+    <%= format_text(WikiPage.titled(Danbooru.config.flag_notice_wiki_page).first.try(&:body)) %>
+  </div>
 
-<%# XXX dtext_field expects there to be a `post_flag` instance variable. %>
-<% @post_flag = post_flag %>
-<%= simple_form_for(@post_flag, format: :js, remote: true) do |f| %>
-  <%= f.hidden_field :post_id %>
-  <%= dtext_field "post_flag", "reason", preview_id: "dtext-preview-for-post-flag", type: "string" %>
-  <%= dtext_preview_button "post_flag", "reason", preview_id: "dtext-preview-for-post-flag" %>
-<% end %>
+  <%# XXX dtext_field expects there to be a `post_flag` instance variable. %>
+  <% @post_flag = post_flag %>
+  <%= simple_form_for(@post_flag, format: :js, remote: true) do |f| %>
+    <%= f.hidden_field :post_id %>
+    <%= dtext_field "post_flag", "reason", preview_id: "dtext-preview-for-post-flag", type: "string" %>
+    <%= dtext_preview_button "post_flag", "reason", preview_id: "dtext-preview-for-post-flag" %>
+  <% end %>
+</div>
diff --git a/app/views/post_flags/new.js.erb b/app/views/post_flags/new.js.erb
new file mode 100644
index 000000000..ec1517cf3
--- /dev/null
+++ b/app/views/post_flags/new.js.erb
@@ -0,0 +1 @@
+Danbooru.Utility.dialog("Flag post", "<%= j render "post_flags/new", post_flag: @post_flag %>");
diff --git a/app/views/post_replacements/_new.html.erb b/app/views/post_replacements/_new.html.erb
index dce3540cb..6cd800187 100644
--- a/app/views/post_replacements/_new.html.erb
+++ b/app/views/post_replacements/_new.html.erb
@@ -1,8 +1,12 @@
-<%= format_text(WikiPage.titled(Danbooru.config.replacement_notice_wiki_page).first.try(&:body)) %>
+<div class="replace-image-dialog-body">
+  <div class="prose">
+    <%= format_text(WikiPage.titled(Danbooru.config.replacement_notice_wiki_page).first.try(&:body)) %>
+  </div>
 
-<%= simple_form_for(post_replacement, url: post_replacements_path(post_id: post_replacement.post_id), method: :post) do |f| %>
-  <%= f.input :replacement_file, label: "File", as: :file %>
-  <%= f.input :replacement_url, label: "Replacement URL", hint: "The source URL to download the replacement from.", as: :string, input_html: { value: post_replacement.post.normalized_source } %>
-  <%= f.input :final_source, label: "Final Source", hint: "If present, the source field will be changed to this after replacement.", as: :string, input_html: { value: post_replacement.post.source } %>
-  <%= f.input :tags, label: "Tags", as: :text, input_html: { value: post_replacement.suggested_tags_for_removal, data: { autocomplete: "tag-edit" } } %>
-<% end %>
+  <%= simple_form_for(post_replacement, url: post_replacements_path(post_id: post_replacement.post_id), method: :post) do |f| %>
+    <%= f.input :replacement_file, label: "File", as: :file %>
+    <%= f.input :replacement_url, label: "Replacement URL", hint: "The source URL to download the replacement from.", as: :string, input_html: { value: post_replacement.post.normalized_source } %>
+    <%= f.input :final_source, label: "Final Source", hint: "If present, the source field will be changed to this after replacement.", as: :string, input_html: { value: post_replacement.post.source } %>
+    <%= f.input :tags, label: "Tags", as: :string, input_html: { value: post_replacement.suggested_tags_for_removal, data: { autocomplete: "tag-edit" } } %>
+  <% end %>
+</div>
diff --git a/app/views/post_replacements/new.html.erb b/app/views/post_replacements/new.html.erb
index 6286252b2..dace2eaa4 100644
--- a/app/views/post_replacements/new.html.erb
+++ b/app/views/post_replacements/new.html.erb
@@ -1,5 +1,5 @@
 <div id="c-post-replacements">
   <div id="a-new">
-    <%= render "new", post_replacement: @post.replacements.new %>
+    <%= render "new", post_replacement: @post_replacement %>
   </div>
 </div>
diff --git a/app/views/post_replacements/new.js.erb b/app/views/post_replacements/new.js.erb
new file mode 100644
index 000000000..6a6943ff1
--- /dev/null
+++ b/app/views/post_replacements/new.js.erb
@@ -0,0 +1 @@
+Danbooru.Utility.dialog("Replace image", "<%= j render "post_replacements/new", post_replacement: @post_replacement %>");
diff --git a/app/views/posts/partials/show/_options.html.erb b/app/views/posts/partials/show/_options.html.erb
index 59545f93b..15352e1c0 100644
--- a/app/views/posts/partials/show/_options.html.erb
+++ b/app/views/posts/partials/show/_options.html.erb
@@ -22,9 +22,9 @@
       <li><span id="status-locked-notice">Status locked</span></li>
     <% else %>
       <% if !post.is_deleted? && !post.is_pending? && !post.is_flagged? %>
-        <li><%= link_to "Flag", new_post_flag_path(:post_id => post.id), :id => "flag" %></li>
+        <li><%= link_to "Flag", new_post_flag_path(post_flag: { post_id: post.id }), id: "flag", remote: true %></li>
       <% elsif post.is_flagged? || post.is_deleted? %>
-        <li><%= link_to "Appeal", new_post_appeal_path(:post_id => post.id), :id => "appeal" %></li>
+        <li><%= link_to "Appeal", new_post_appeal_path(post_appeal: { post_id: post.id }), id: "appeal", remote: true %></li>
       <% end %>
 
       <% if CurrentUser.can_approve_posts? %>
@@ -53,7 +53,7 @@
         <% end %>
 
         <% if CurrentUser.is_moderator? %>
-          <li><%= link_to "Replace Image", new_post_replacement_path(:post_id => post.id), :id => "replace-image" %></li>
+          <li><%= link_to "Replace Image", new_post_replacement_path(post_id: post.id), id: "replace-image", remote: true %></li>
           <li><%= link_to "Down vote report", reports_down_voting_post_path(post_id: post.id) %></li>
         <% end %>
       <% end %>
diff --git a/app/views/posts/show.html.erb b/app/views/posts/show.html.erb
index 1388db82f..a6b15d4a1 100644
--- a/app/views/posts/show.html.erb
+++ b/app/views/posts/show.html.erb
@@ -135,18 +135,6 @@
     </section>
   </div>
 
-  <div id="flag-dialog" class="prose" title="Flag post" style="display: none;">
-    <%= render "post_flags/new", post_flag: @post.flags.new %>
-  </div>
-
-  <div id="appeal-dialog" class="prose" title="Appeal post" style="display: none;">
-    <%= render "post_appeals/new", post_appeal: @post.appeals.new %>
-  </div>
-
-  <div id="replace-image-dialog" class="prose" title="Replace image" style="display: none;">
-    <%= render "post_replacements/new", post_replacement: @post.replacements.new %>
-  </div>
-
   <div id="add-to-pool-dialog" title="Add to pool" style="display: none;">
     <%= render "pool_elements/new" %>
   </div>