How to block a whole page?

When you get into specific areas such as this (like how to handle a slider), then you get into more advanced customization topics.

The simple solution is to set up a custom process to redirect the user from blocked content to log in. This can be configured using the wpmem_redirect_to_login() function in the plugin’s API.

There would be other possible approaches to handling this as well, but it would depend entirely on the slider and how it works/is loaded.

Another very simple solution is the plugin’s Advanced Options extension, which is available to support subscribers. The A|O extension has a number of settings that allow you to set up redirects to the login based on various criteria. It allows you to redirect everything to login, just blocked content, or just specific posts/pages.

I didn’t expect this to be as tedious to workaround. Although I neither expect there to be a workaround, to be fair. Thank you for pointing me in the right direction.

Just for the record, my concern is not specifically about the slider, that was just an example. What I’m looking for is for a simple way to show a blank page with just the WP-Member login form when someone tries to access any blocked page.

Are there any plans to implement such feature in a future update?

What I’m looking for is for a simple way to show a blank page with just the WP-Member login form when someone tries to access any blocked page.

On just a basic page, that’s pretty much what the plugin does (unless what you mean by “just the WP-Member login form” means nothing else, like header and navigation).

While the plugin is very extensible, it does have a specific set of usage assumptions. Probably the best description of that with regards to blocking content is this:
https://rocketgeek.com/blog/how-the-plugin-handles-blocking-content/

Can things be added into the plugin? Yes. But my design philosophy is more like Matt Mullenweg’s in that I don’t believe in offering a setting for every possible option that could exist. If I did, that would make the process more confusing, not less.

Instead, the plugin is built around a core philosophy of simple use, simple setup, with a broad framework of action and filter hooks as well as a user accessible API for customizing just about anything you want.

I think this review of the plugin by Chris Lema actually points this out better than I am able to. Chris summed it up with this:

There’s a difference between a complete plugin and a plugin that tries to do everything. You can be complete without doing everything by targeting certain problems and solving them well.

It may have seemed complex based on my original response because the link to the wpmem_redirect_to_login() function was somehow bad in that post. The link should be this:

https://rocketgeek.com/plugins/wp-members/docs/api-functions/wpmem_redirect_to_login/

That API function can be easily used to redirect blocked content to a login page. And that can be done the way you want it to happen, not the way I force you to do it (which is what essentially happens when the plugin has something built into it).

Are there any plans to implement such feature in a future update?

Maybe… but for now, it is available in the Advanced Options extension that I mentioned:

https://rocketgeek.com/plugins/wp-members/extensions/advanced-options/

While the Advanced Options extension is currently only available to support site subscribers, I will be soon offering certain extensions for purchase individually rather than the one-price-for-everything model that exists now. However, with full disclosure, when that happens, the price for the one-for-all will also be going up, so the current pricing is a very solid value.

I know that’s probably a longer than necessary answer, but it’s a core topic (blocking content). I hope it adds some (useful) clarity to the whole scope. If not, let me know.