diff --git a/lib/classes/output/icon_system_fontawesome.php b/lib/classes/output/icon_system_fontawesome.php
index b684751c384..e5e8ec76d31 100644
--- a/lib/classes/output/icon_system_fontawesome.php
+++ b/lib/classes/output/icon_system_fontawesome.php
@@ -294,6 +294,7 @@ class icon_system_fontawesome extends icon_system_font {
             'core:i/scheduled' => 'fa-calendar-check-o',
             'core:i/search' => 'fa-search',
             'core:i/section' => 'fa-folder-o',
+            'core:i/sendmessage' => 'fa-paper-plane',
             'core:i/settings' => 'fa-cog',
             'core:i/show' => 'fa-eye-slash',
             'core:i/siteevent' => 'fa-globe',
@@ -332,6 +333,7 @@ class icon_system_fontawesome extends icon_system_font {
             'core:t/collapsed_empty' => 'fa-plus-square-o',
             'core:t/collapsed_rtl' => 'fa-plus-square',
             'core:t/collapsed' => 'fa-plus-square',
+            'core:t/collapsedcaret' => 'fa-caret-right',
             'core:t/contextmenu' => 'fa-cog',
             'core:t/copy' => 'fa-copy',
             'core:t/delete' => 'fa-trash',
diff --git a/pix/i/sendmessage.png b/pix/i/sendmessage.png
new file mode 100644
index 00000000000..dcf25dc4937
Binary files /dev/null and b/pix/i/sendmessage.png differ
diff --git a/pix/i/sendmessage.svg b/pix/i/sendmessage.svg
new file mode 100644
index 00000000000..48c19f159a2
--- /dev/null
+++ b/pix/i/sendmessage.svg
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="12pt" height="12pt" viewBox="0 0 12 12" version="1.1">
+<g id="surface1">
+<path style=" stroke:none;fill-rule:nonzero;fill:rgb(60%,60%,60%);fill-opacity:1;" d="M 11.8125 0.0742188 C 11.960938 0.179688 12.019531 0.324219 11.992188 0.503906 L 10.277344 10.789062 C 10.257812 10.917969 10.183594 11.019531 10.066406 11.089844 C 10.003906 11.125 9.933594 11.144531 9.855469 11.144531 C 9.808594 11.144531 9.753906 11.132812 9.695312 11.109375 L 6.664062 9.871094 L 5.042969 11.847656 C 4.960938 11.949219 4.851562 12 4.714844 12 C 4.65625 12 4.605469 11.992188 4.566406 11.972656 C 4.480469 11.941406 4.414062 11.890625 4.363281 11.816406 C 4.3125 11.742188 4.285156 11.660156 4.285156 11.570312 L 4.285156 9.234375 L 10.070312 2.144531 L 2.914062 8.335938 L 0.269531 7.253906 C 0.101562 7.191406 0.0117188 7.066406 0 6.882812 C -0.0078125 6.707031 0.0625 6.574219 0.214844 6.488281 L 11.355469 0.0585938 C 11.425781 0.0195312 11.496094 0 11.570312 0 C 11.660156 0 11.742188 0.0234375 11.8125 0.0742188 Z M 11.8125 0.0742188 "/>
+</g>
+</svg>
diff --git a/pix/i/trash.png b/pix/i/trash.png
new file mode 100644
index 00000000000..dd54a6efd43
Binary files /dev/null and b/pix/i/trash.png differ
diff --git a/pix/i/trash.svg b/pix/i/trash.svg
new file mode 100644
index 00000000000..1d36252150a
--- /dev/null
+++ b/pix/i/trash.svg
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="12pt" height="12pt" viewBox="0 0 12 12" version="1.1">
+<g id="surface1">
+<path style=" stroke:none;fill-rule:nonzero;fill:rgb(60%,60%,60%);fill-opacity:1;" d="M 4.714844 9.214844 L 4.714844 4.5 C 4.714844 4.4375 4.695312 4.386719 4.652344 4.347656 C 4.613281 4.304688 4.5625 4.285156 4.5 4.285156 L 4.070312 4.285156 C 4.007812 4.285156 3.957031 4.304688 3.917969 4.347656 C 3.878906 4.386719 3.855469 4.4375 3.855469 4.5 L 3.855469 9.214844 C 3.855469 9.277344 3.878906 9.328125 3.917969 9.367188 C 3.957031 9.410156 4.007812 9.429688 4.070312 9.429688 L 4.5 9.429688 C 4.5625 9.429688 4.613281 9.410156 4.652344 9.367188 C 4.695312 9.328125 4.714844 9.277344 4.714844 9.214844 Z M 6.429688 9.214844 L 6.429688 4.5 C 6.429688 4.4375 6.410156 4.386719 6.367188 4.347656 C 6.328125 4.304688 6.277344 4.285156 6.214844 4.285156 L 5.785156 4.285156 C 5.722656 4.285156 5.671875 4.304688 5.632812 4.347656 C 5.589844 4.386719 5.570312 4.4375 5.570312 4.5 L 5.570312 9.214844 C 5.570312 9.277344 5.589844 9.328125 5.632812 9.367188 C 5.671875 9.410156 5.722656 9.429688 5.785156 9.429688 L 6.214844 9.429688 C 6.277344 9.429688 6.328125 9.410156 6.367188 9.367188 C 6.410156 9.328125 6.429688 9.277344 6.429688 9.214844 Z M 8.144531 9.214844 L 8.144531 4.5 C 8.144531 4.4375 8.121094 4.386719 8.082031 4.347656 C 8.042969 4.304688 7.992188 4.285156 7.929688 4.285156 L 7.5 4.285156 C 7.4375 4.285156 7.386719 4.304688 7.347656 4.347656 C 7.304688 4.386719 7.285156 4.4375 7.285156 4.5 L 7.285156 9.214844 C 7.285156 9.277344 7.304688 9.328125 7.347656 9.367188 C 7.386719 9.410156 7.4375 9.429688 7.5 9.429688 L 7.929688 9.429688 C 7.992188 9.429688 8.042969 9.410156 8.082031 9.367188 C 8.121094 9.328125 8.144531 9.277344 8.144531 9.214844 Z M 4.5 2.570312 L 7.5 2.570312 L 7.179688 1.789062 C 7.148438 1.746094 7.109375 1.722656 7.066406 1.714844 L 4.941406 1.714844 C 4.898438 1.722656 4.859375 1.746094 4.828125 1.789062 Z M 10.714844 2.785156 L 10.714844 3.214844 C 10.714844 3.277344 10.695312 3.328125 10.652344 3.367188 C 10.613281 3.410156 10.5625 3.429688 10.5 3.429688 L 9.855469 3.429688 L 9.855469 9.777344 C 9.855469 10.148438 9.753906 10.46875 9.542969 10.738281 C 9.332031 11.007812 9.082031 11.144531 8.785156 11.144531 L 3.214844 11.144531 C 2.917969 11.144531 2.667969 11.011719 2.457031 10.75 C 2.246094 10.488281 2.144531 10.175781 2.144531 9.804688 L 2.144531 3.429688 L 1.5 3.429688 C 1.4375 3.429688 1.386719 3.410156 1.347656 3.367188 C 1.304688 3.328125 1.285156 3.277344 1.285156 3.214844 L 1.285156 2.785156 C 1.285156 2.722656 1.304688 2.671875 1.347656 2.632812 C 1.386719 2.589844 1.4375 2.570312 1.5 2.570312 L 3.570312 2.570312 L 4.039062 1.453125 C 4.105469 1.289062 4.226562 1.148438 4.398438 1.03125 C 4.574219 0.914062 4.75 0.855469 4.929688 0.855469 L 7.070312 0.855469 C 7.25 0.855469 7.425781 0.914062 7.601562 1.03125 C 7.773438 1.148438 7.894531 1.289062 7.960938 1.453125 L 8.429688 2.570312 L 10.5 2.570312 C 10.5625 2.570312 10.613281 2.589844 10.652344 2.632812 C 10.695312 2.671875 10.714844 2.722656 10.714844 2.785156 Z M 10.714844 2.785156 "/>
+</g>
+</svg>
diff --git a/pix/i/window_close.png b/pix/i/window_close.png
new file mode 100644
index 00000000000..a57632ea201
Binary files /dev/null and b/pix/i/window_close.png differ
diff --git a/pix/i/window_close.svg b/pix/i/window_close.svg
new file mode 100644
index 00000000000..b4ad0a6985c
--- /dev/null
+++ b/pix/i/window_close.svg
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="12pt" height="12pt" viewBox="0 0 12 12" version="1.1">
+<g id="surface1">
+<path style=" stroke:none;fill-rule:nonzero;fill:rgb(60%,60%,60%);fill-opacity:1;" d="M 7.867188 8.847656 L 8.847656 7.867188 C 8.890625 7.824219 8.914062 7.773438 8.914062 7.714844 C 8.914062 7.65625 8.890625 7.605469 8.847656 7.558594 L 7.285156 6 L 8.847656 4.441406 C 8.890625 4.394531 8.914062 4.34375 8.914062 4.285156 C 8.914062 4.226562 8.890625 4.175781 8.847656 4.132812 L 7.867188 3.152344 C 7.824219 3.109375 7.773438 3.085938 7.714844 3.085938 C 7.65625 3.085938 7.605469 3.109375 7.558594 3.152344 L 6 4.714844 L 4.441406 3.152344 C 4.394531 3.109375 4.34375 3.085938 4.285156 3.085938 C 4.226562 3.085938 4.175781 3.109375 4.132812 3.152344 L 3.152344 4.132812 C 3.109375 4.175781 3.085938 4.226562 3.085938 4.285156 C 3.085938 4.34375 3.109375 4.394531 3.152344 4.441406 L 4.714844 6 L 3.152344 7.558594 C 3.109375 7.605469 3.085938 7.65625 3.085938 7.714844 C 3.085938 7.773438 3.109375 7.824219 3.152344 7.867188 L 4.132812 8.847656 C 4.175781 8.890625 4.226562 8.914062 4.285156 8.914062 C 4.34375 8.914062 4.394531 8.890625 4.441406 8.847656 L 6 7.285156 L 7.558594 8.847656 C 7.605469 8.890625 7.65625 8.914062 7.714844 8.914062 C 7.773438 8.914062 7.824219 8.890625 7.867188 8.847656 Z M 12 1.929688 L 12 10.070312 C 12 10.367188 11.894531 10.617188 11.683594 10.828125 C 11.476562 11.039062 11.222656 11.144531 10.929688 11.144531 L 1.070312 11.144531 C 0.777344 11.144531 0.523438 11.039062 0.316406 10.828125 C 0.105469 10.617188 0 10.367188 0 10.070312 L 0 1.929688 C 0 1.632812 0.105469 1.382812 0.316406 1.171875 C 0.523438 0.960938 0.777344 0.855469 1.070312 0.855469 L 10.929688 0.855469 C 11.222656 0.855469 11.476562 0.960938 11.683594 1.171875 C 11.894531 1.382812 12 1.632812 12 1.929688 Z M 12 1.929688 "/>
+</g>
+</svg>
diff --git a/pix/t/sendmessage.png b/pix/t/sendmessage.png
new file mode 100644
index 00000000000..dcf25dc4937
Binary files /dev/null and b/pix/t/sendmessage.png differ
diff --git a/pix/t/sendmessage.svg b/pix/t/sendmessage.svg
new file mode 100644
index 00000000000..9755f874b23
--- /dev/null
+++ b/pix/t/sendmessage.svg
@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="utf-8"?>
+<svg width="12" height="12" viewBox="0 0 12 12" xmlns="http://www.w3.org/2000/svg"><path d="M1764 11q33 24 27 64l-256 1536q-5 29-32 45-14 8-31 8-11 0-24-5l-453-185-242 295q-18 23-49 23-13 0-22-4-19-7-30.5-23.5t-11.5-36.5v-349l864-1059-1069 925-395-162q-37-14-40-55-2-40 32-59l1664-960q15-9 32-9 20 0 36 11z" fill="#999"/></svg>
\ No newline at end of file
diff --git a/theme/boost/scss/moodle/icons.scss b/theme/boost/scss/moodle/icons.scss
index 7defdf20652..a5a2748d646 100644
--- a/theme/boost/scss/moodle/icons.scss
+++ b/theme/boost/scss/moodle/icons.scss
@@ -90,6 +90,7 @@ $iconsizes: map-merge((
         .icon {
             height: $length !important; /* stylelint-disable-line declaration-no-important */
             width: $length !important; /* stylelint-disable-line declaration-no-important */
+            font-size: $length !important; /* stylelint-disable-line declaration-no-important */
         }
     }
 }
diff --git a/theme/boost/style/moodle.css b/theme/boost/style/moodle.css
index 44c7096408a..68dc4d76694 100644
--- a/theme/boost/style/moodle.css
+++ b/theme/boost/style/moodle.css
@@ -10518,36 +10518,48 @@ div.editor_atto_toolbar button .icon {
   height: 0 !important;
   /* stylelint-disable-line declaration-no-important */
   width: 0 !important;
+  /* stylelint-disable-line declaration-no-important */
+  font-size: 0 !important;
   /* stylelint-disable-line declaration-no-important */ }
 
 .icon-size-1 .icon {
   height: 4px !important;
   /* stylelint-disable-line declaration-no-important */
   width: 4px !important;
+  /* stylelint-disable-line declaration-no-important */
+  font-size: 4px !important;
   /* stylelint-disable-line declaration-no-important */ }
 
 .icon-size-2 .icon {
   height: 8px !important;
   /* stylelint-disable-line declaration-no-important */
   width: 8px !important;
+  /* stylelint-disable-line declaration-no-important */
+  font-size: 8px !important;
   /* stylelint-disable-line declaration-no-important */ }
 
 .icon-size-3 .icon {
   height: 16px !important;
   /* stylelint-disable-line declaration-no-important */
   width: 16px !important;
+  /* stylelint-disable-line declaration-no-important */
+  font-size: 16px !important;
   /* stylelint-disable-line declaration-no-important */ }
 
 .icon-size-4 .icon {
   height: 24px !important;
   /* stylelint-disable-line declaration-no-important */
   width: 24px !important;
+  /* stylelint-disable-line declaration-no-important */
+  font-size: 24px !important;
   /* stylelint-disable-line declaration-no-important */ }
 
 .icon-size-5 .icon {
   height: 48px !important;
   /* stylelint-disable-line declaration-no-important */
   width: 48px !important;
+  /* stylelint-disable-line declaration-no-important */
+  font-size: 48px !important;
   /* stylelint-disable-line declaration-no-important */ }
 
 .helplink .icon {