Sorry for the slow response. We released an update today. Did that help with this issue? If not, can you send a little more information about your setup? What theme are you using? What is your URL? What version of PHP are you running?
We look forward to your reply.
Hey.
Thanks for your reply.
The update did not help.
theme : https://goo.gl/uXGzo3
php : 5.6.29
I activated with RTL and I am not able to replicate this issue.

If you have not already done so could you run a plugin conflict test? Deactivate all of your plugins and reactivate each plugin until the error returns. If you share your website URL we can take a closer look. Thank you.
Hi Daniel,
It looks like there’s something changing the width of default WP widgets page.
If I put your and my WP admin next to each other you can see that your widgets are double the width than they should be, see this screenshot:
https://screencast.com/t/vd1UQHL8cJFu
Here you can see that even with CustomSidebars my widgets are not changing width:
https://screencast.com/t/HW6rLs7HCup
Can you try disabling CustomSidebars on your site and see if the widgets are still wider than they should be?
If they are then try disabling your plugins one by one to determine which one is causing it.
Cheers,
Predrag
Thank you for using Custom Sidebars. Were you able to find the conflict? I am going to mark this topic resolved because we haven’t heard from you in awhile. If this issue was not resolved we can reopen it. Thanks again!