I am testing ubuntu studio 18.04 beta final and it affects openshot 2.4.1 and flowblade 1.16
<b>Flowblade<b>
<pre>
(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.334</font>: Theme parsing error: gtk.css:597:14: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.334</font>: Theme parsing error: gtk.css:597:14: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.334</font>: Theme parsing error: gtk.css:600:17: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.337</font>: Theme parsing error: gtk.css:784:14: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.337</font>: Theme parsing error: gtk.css:784:14: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.337</font>: Theme parsing error: gtk.css:787:17: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.341</font>: Theme parsing error: gtk.css:1096:14: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.341</font>: Theme parsing error: gtk.css:1096:14: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.342</font>: Theme parsing error: gtk.css:1099:17: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.357</font>: Theme parsing error: gtk.css:2286:8: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.357</font>: Theme parsing error: gtk.css:2286:18: Using Pango syntax for the font: style property is deprecated; please use CSS syntax

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.357</font>: Theme parsing error: gtk.css:2291:8: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.357</font>: Theme parsing error: gtk.css:2291:18: Using Pango syntax for the font: style property is deprecated; please use CSS syntax

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.376</font>: Theme parsing error: gtk.css:4357:14: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.376</font>: Theme parsing error: gtk.css:4357:14: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.376</font>: Theme parsing error: gtk.css:4419:12: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.376</font>: Theme parsing error: gtk.css:4419:12: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.376</font>: Theme parsing error: gtk.css:4428:16: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.376</font>: Theme parsing error: gtk.css:4428:16: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.377</font>: Theme parsing error: gtk.css:4443:22: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.377</font>: Theme parsing error: gtk.css:4443:22: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.377</font>: Theme parsing error: gtk.css:4499:12: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.377</font>: Theme parsing error: gtk.css:4501:16: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.377</font>: Theme parsing error: gtk.css:4501:16: Expected a string.

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.378</font>: Theme parsing error: gtk.css:4549:12: not a number

(flowblade:3098): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">23:58:21.378</font>: Theme parsing error: gtk.css:4549:12: Expected a string.</pre>

<b>openshot</b>
<pre>Loaded modules from installed directory: /usr/lib/python3/dist-packages/openshot_qt
      launch:INFO ------------------------------------------------
      launch:INFO    OpenShot (version 2.4.1)
      launch:INFO ------------------------------------------------

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.344</font>: Theme parsing error: gtk.css:597:14: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.344</font>: Theme parsing error: gtk.css:597:14: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.345</font>: Theme parsing error: gtk.css:600:17: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.347</font>: Theme parsing error: gtk.css:784:14: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.347</font>: Theme parsing error: gtk.css:784:14: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.347</font>: Theme parsing error: gtk.css:787:17: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.352</font>: Theme parsing error: gtk.css:1096:14: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.352</font>: Theme parsing error: gtk.css:1096:14: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.352</font>: Theme parsing error: gtk.css:1099:17: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.367</font>: Theme parsing error: gtk.css:2286:8: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.367</font>: Theme parsing error: gtk.css:2286:18: Using Pango syntax for the font: style property is deprecated; please use CSS syntax

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.367</font>: Theme parsing error: gtk.css:2291:8: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.367</font>: Theme parsing error: gtk.css:2291:18: Using Pango syntax for the font: style property is deprecated; please use CSS syntax

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.384</font>: Theme parsing error: gtk.css:4357:14: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.384</font>: Theme parsing error: gtk.css:4357:14: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.384</font>: Theme parsing error: gtk.css:4419:12: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.385</font>: Theme parsing error: gtk.css:4419:12: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.385</font>: Theme parsing error: gtk.css:4428:16: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.385</font>: Theme parsing error: gtk.css:4428:16: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.385</font>: Theme parsing error: gtk.css:4443:22: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.385</font>: Theme parsing error: gtk.css:4443:22: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.386</font>: Theme parsing error: gtk.css:4499:12: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.386</font>: Theme parsing error: gtk.css:4501:16: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.386</font>: Theme parsing error: gtk.css:4501:16: Expected a string.

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.386</font>: Theme parsing error: gtk.css:4549:12: not a number

(python3:3302): Gtk-<font color="#DED82C"><b>WARNING</b></font> **: <font color="#0039AA">00:05:54.386</font>: Theme parsing error: gtk.css:4549:12: Expected a string.
</pre>