Prevent hiding handles by clicking on handles

ts/components/ButtonDropdown.svelte

@@ -19,14 +19,20 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 <ButtonToolbar
     {id}
-    class={`dropdown-menu btn-dropdown-menu ${className}`}
+    class="dropdown-menu btn-dropdown-menu {className}"
     wrap={false}
     {api}
 >
-    <slot />
+    <div on:mousedown|preventDefault|stopPropagation>
+        <slot />
+    </div>
 </ButtonToolbar>
 
 <style lang="scss">
+    div {
+        display: contents;
+    }
+
     :global(.dropdown-menu.btn-dropdown-menu) {
         display: none;
         min-width: 0;

ts/components/DropdownMenu.svelte

@@ -16,7 +16,13 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     setContext(dropdownKey, null);
 </script>
 
-<div {id} class="dropdown-menu" class:show aria-labelledby={labelledby}>
+<div
+    {id}
+    class="dropdown-menu"
+    class:show
+    aria-labelledby={labelledby}
+    on:mousedown|preventDefault|stopPropagation
+>
     <div class="dropdown-content {className}">
         <slot />
     </div>

ts/editor/MathjaxHandleEditor.svelte

@@ -41,23 +41,19 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     });
 </script>
 
-<!-- <textarea bind:value use:openCodemirror /> -->
 <div
     on:click|stopPropagation
     on:focus|stopPropagation
     on:keydown|stopPropagation
-    on:focusin|stopPropagation
     on:keyup|stopPropagation
+    on:focusin|stopPropagation
+    on:mousedown|preventDefault|stopPropagation
     on:mouseup|stopPropagation
 >
     <!-- TODO no focusin for now, as EditingArea will defer to Editable/Codable -->
     <textarea
         bind:this={textarea}
         value={initialValue}
-        on:mouseup|preventDefault|stopPropagation
-        on:keyup|stopPropagation
-        on:click|stopPropagation
-        on:focusin|stopPropagation
         on:input={onInput}
         use:openCodemirror
     />