BACKGROUND
Run into an issue implementing the answer to this question, How to recreate Contact, Account, & Opportunity homepages with Visualforce pages? – that being:
There appears to be a "bug" with this approach, though it's not a deal
breaker for me; meaning I still plan to use this approach in part
because as a result of the bug being present on 100% of the tabs
displayed, it's less noticeable. So, bug is that the "real" accounts
tab, which is hidden, is the tab that's shown as being active, even
though it's not; meaning if you have the real & custom tabs displayed,
click the custom tab, the real tab is highlighted as being selected
even though it is not. Played around with both the code, tab-names,
etc. and nothing appears to fix this.
eyescream was kind enough to reply my comment saying:
I thought you were going to override the standard tab with this? Go to
Setup > Accounts > Buttons, Links and Actions and hit "Edit" next to
"Tab". Change the code to (no std controller specified) and it should become
selectable. If you still need server-side checks – just use regular
controller and not an extension class.
Thing is there appears to be a few issues, first issue being that I'm unable to get it to work, and the next being that it appears there's some code in the "Setup > Build > Customize > [Accounts,Contacts,Opportunities] > Buttons, Links, and Actions" that is from the Nonprofit Starter Pack. As such, give these appears to be more of a new question, than a request for clarification, and it's likely that you seeing what I'm seeing would be of use, I've posted a new question.
Efforts Made
(1) Updated the Visualforce code for the custom contact tab/page by replacing <apex:page standardController="Account" readonly="true">
with <apex:page readonly="true" tabStyle="Contact">
Here's the text version of the code above if it's of use:
<apex:page readonly="true" tabStyle="Contact">
<apex:sectionHeader title="{!$objectType.Contact.LabelPlural}" subtitle="Home"/>
<apex:ListViews type="Contact" />
</apex:page>
(2) Modified the contact tab configs here, "Setup > Build > Customize > Contacts > Buttons, Links, and Actions" by selecting "Override With: Visualforce page", selecting the related Visualforce page, and saving the change:
(3) Moved the custom tab next to the default tab and tested to see if the bug was fixed by clicking the home tab, then the custom tab; the result was that the page for the custom tab was displayed, but the tab for the default contact page was highlighted.
Here's a pic of what I'm seeing, the default contact tab is on the left, and the custom contact page tab is on the right:
Nonprofit Starter Pack Customizations
As mentioned above, there are some Nonprofit Starter Pack (which are managed packages from the Salesforce Foundation) listed within the over item in "Setup > Build > Customize > Contacts > Buttons, Links, and Actions" but the default-tab-override item was set to the default, so I'm guessing that the other code is unrelated to the current issue of me attempt to override the default-contact-tab. Happy to post the code if it's of use.
Best Answer
Per eyescream's request, I'm posting his answer left in the comments above here:
I've verified this was the issue, and that that his additional suggestion works too, that being:
Worth noting that I tested the above on non-sysadmin user, and the user is able to view the default page if they know the parameters to pass in the URL; which makes sense.