This modification takes a thumbnail attachment attached to the first post of the topic and shows this thumbnail on the topic listing page of a forum.

Version 4.2.1
!Group by fixes for SMF 2.1.x

Version 4.2
!Fixes for image distortion and styling for SMF 2.1.X thanks to @rjen

Version 4.1
!Hide thumbnail column if users don't have permissions to view attachments

Version 4.0
!Fixed a case where if you are just using linked images the column for thumbnail topic will not appear

Version 3.0.1
!Fixed bug SMF 2.0.x not saving new board thumbnail topic settings

Version 3.0
+Added support for img tags inside the first forum post for SMF 2.0 thanks to br360
Setting to control height width found under Modification Settings. Use zero in both values to disable it.
!Fixed board level permissions to hide thumbnails

Version 2.0
Big thanks to dougiefresh for this update.
+Adds an interface in the manage boards area to checkbox if the board has the thumbnail topic system enabled for it or not.

Version 1.1
!Fixed showing an image if there was another attachment of a different type before it.
!Also fixed issue with posts disappearing.

ThumbnailTopic.zip 17.79 KB v4.2 1.1.21, 2.0 RC2, 2.0 RC3, 2.0.19, 2.0 RC4, 2.0 RC5, 2.1.2

ThumbnailTopic.zip 17.83 KB v4.2.1 1.1.21, 2.0 RC2, 2.0 RC3, 2.0.19, 2.0 RC4, 2.0 RC5, 2.1.2

Manual installation info 1.1.12 1.1.13 1.1.14 1.1.15 1.1.16 1.1.17 1.1.18 1.1.19 1.1.20 1.1.21 2.0 2.0.9 2.0.10 2.0.11 2.0.12 2.0.13 2.0.14 2.0.15 2.0.16 2.0.17 2.0.18 2.0.19 2.1.2