🎨(themes): Fixes Windows button UI issues in #1649

internal_packages/thread-list/stylesheets/thread-list.less

@@ -301,9 +301,9 @@
 .thread-list .list-item .list-column-HoverActions {
   display:none;
   .action {
-    display:inline-block;
+    display: inline-block;
     background-size: 100%;
-    zoom:0.5;
+    zoom: 0.5;
     width: 81px;
     height: 51px;
     margin: 9px 16px 0 16px;
@@ -324,15 +324,6 @@ body.platform-win32 {
       border: 0;
       margin: 9px 0 0 0;
     }
-    .action.action-archive {
-      background: url(@archive-img) center no-repeat;
-    }
-    .action.action-trash {
-      background: url(@trash-img) center no-repeat;
-    }
-    .action.action-snooze {
-      background: url(@snooze-img) center no-repeat;
-    }
   }
 }
 .thread-list .list-item:hover .list-column-HoverActions {

internal_packages/ui-darkside/styles/darkside.less

@@ -698,6 +698,10 @@ body.is-blurred .list-tabular .list-tabular-item.keyboard-cursor {
   background: transparent;
 }
 
+body.platform-win32 .sheet-toolbar-container .btn-toolbar:hover {
+  background: none;
+}
+
 // Centering vertially without magic numbers
 .layout-mode-popout .toolbar-window-controls {
   margin-top: 0;

src/sheet-toolbar.cjsx

@@ -105,9 +105,9 @@ class ToolbarMenuControl extends React.Component
   @displayName: 'ToolbarMenuControl'
   render: =>
     <div className="toolbar-menu-control">
-      <div className="btn btn-toolbar" onClick={@_openMenu}>
+      <button className="btn btn-toolbar" onClick={@_openMenu}>
         <RetinaImg name="windows-menu-icon.png" mode={RetinaImg.Mode.ContentIsMask} />
-      </div>
+      </button>
     </div>
 
   _openMenu: =>

static/workspace.less

@@ -390,7 +390,7 @@ body.platform-win32 {
       box-shadow: none;
       background: none;
       &:hover {
-        background: #e5e5e5;
+        background: darken(@list-hover-bg, 5%);
       }
     }
   }