theme: Move .workspace-thumbnail* into _workspace-thumbnails.scss

While workspace switcher is an OSD, workspace pager is an overview
panel. So it makes more sense to separate them into different
stylesheets.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/938

data/theme/gnome-shell-sass/_widgets.scss

@@ -39,6 +39,7 @@
 @import 'widgets/search-results';
 @import 'widgets/app-grid';
 @import 'widgets/dash';
+@import 'widgets/workspace-thumbnails';
 // A11y / misc
 @import 'widgets/a11y';
 @import 'widgets/misc';

data/theme/gnome-shell-sass/widgets/_workspace-switcher.scss

@@ -34,36 +34,3 @@
   border-radius: $base_border_radius + 3px;
   color: $selected_fg_color;
 }
-
-/* Workspace pager */
-
-// thumbnails in overview
-.workspace-thumbnails { 
-  @extend %overview_panel;
-  visible-width: 32px; //amount visible before hover
-  spacing: $base_spacing;
-  padding: $base_padding;
-
-  border-radius: $modal_radius 0 0 $modal_radius;
-  border-right-width: 0;
-
-  &:rtl {
-    border-radius: 0 $modal_radius $modal_radius 0; 
-    border-left-width: 0;
-  }
-
-  // drag and drop indicator
-  .placeholder {
-    background-image: url("resource:///org/gnome/shell/theme/dash-placeholder.svg");
-    background-size: contain;
-    height: 24px;
-  }
-}
-
-// selected indicator
-.workspace-thumbnail-indicator {
-  border: 3px solid $selected_bg_color;
-  border-radius: 3px;
-  padding: 0px;
-  // background-color: transparentize($selected_bg_color, 0.9);
-}

data/theme/gnome-shell-sass/widgets/_workspace-thumbnails.scss

@@ -0,0 +1,32 @@
+/* Workspace pager */
+
+// thumbnails in overview
+.workspace-thumbnails {
+  @extend %overview_panel;
+  visible-width: 32px; //amount visible before hover
+  spacing: $base_spacing;
+  padding: $base_padding;
+
+  border-radius: $modal_radius 0 0 $modal_radius;
+  border-right-width: 0;
+
+  &:rtl {
+    border-radius: 0 $modal_radius $modal_radius 0;
+    border-left-width: 0;
+  }
+
+  // drag and drop indicator
+  .placeholder {
+    background-image: url("resource:///org/gnome/shell/theme/dash-placeholder.svg");
+    background-size: contain;
+    height: 24px;
+  }
+}
+
+// selected indicator
+.workspace-thumbnail-indicator {
+  border: 3px solid $selected_bg_color;
+  border-radius: 3px;
+  padding: 0px;
+  // background-color: transparentize($selected_bg_color, 0.9);
+}

data/theme/meson.build

@@ -38,7 +38,8 @@ theme_sources = files([
   'gnome-shell-sass/widgets/_switches.scss',
   'gnome-shell-sass/widgets/_tiled-previews.scss',
   'gnome-shell-sass/widgets/_window-picker.scss',
-  'gnome-shell-sass/widgets/_workspace-switcher.scss'
+  'gnome-shell-sass/widgets/_workspace-switcher.scss',
+  'gnome-shell-sass/widgets/_workspace-thumbnails.scss'
 ])
 
 styles = [