This exact issue has been already discussed before with woritem [16321](https://ajaxcontroltoolkit.codeplex.com/workitem/16321). I was not able to find any other recent discussion about it.
I invite to read that report because symptoms are very well explained by the author.
I updated toolkit version from 30930 (Sep 2009) to 7.1213 (Dec 2013) on a project containing a complex implementation of TabContainer. Before the update I had no issue at all with that page and TabContainer in general, but as soon as I referenced new toolkit version I found out some strange behaviors.
I reduced it all in a very simple, standalone page, attached to this post.
Basically what happens is that when you set one or more tab to be invisible (no matter whether you do it by the attribute on tag declaration or in the code-behind), TabContainer starts to display mixed-content tabs after ActiveTabChanged event, when index requested is equals or greater than the one of the not visible.
Page attached shows it very clearly.
Note: none of the workarounds proposed in the old workitem is working in my environment.
Target framework 3.5, Toolkit version 7.1213, IIS 7.5, Windows 7 64 bit
Comments: Hi dbarney, I was not worried about html content visibility since in my case this was not critical (data in disabled tabs are not sensitve). Anyway, as far as I can tell, I can confirm that in page source you can find all tab headers html code, but tabs content is visible just for the active one: workaround should work for your case, either. My solution has been online on production server for about 2 months now, it seems to work pretty solid after all. Hope it helps, let me know.
I invite to read that report because symptoms are very well explained by the author.
I updated toolkit version from 30930 (Sep 2009) to 7.1213 (Dec 2013) on a project containing a complex implementation of TabContainer. Before the update I had no issue at all with that page and TabContainer in general, but as soon as I referenced new toolkit version I found out some strange behaviors.
I reduced it all in a very simple, standalone page, attached to this post.
Basically what happens is that when you set one or more tab to be invisible (no matter whether you do it by the attribute on tag declaration or in the code-behind), TabContainer starts to display mixed-content tabs after ActiveTabChanged event, when index requested is equals or greater than the one of the not visible.
Page attached shows it very clearly.
Note: none of the workarounds proposed in the old workitem is working in my environment.
Target framework 3.5, Toolkit version 7.1213, IIS 7.5, Windows 7 64 bit
Comments: Hi dbarney, I was not worried about html content visibility since in my case this was not critical (data in disabled tabs are not sensitve). Anyway, as far as I can tell, I can confirm that in page source you can find all tab headers html code, but tabs content is visible just for the active one: workaround should work for your case, either. My solution has been online on production server for about 2 months now, it seems to work pretty solid after all. Hope it helps, let me know.