Create More Intuitive Way to Select Multiple Modules

I am wondering if this is potentially a duplicate of: #2930585: Suggest using the chosen module

We could make the module list a list of checkboxes but that can grow very big too. Though arguably a permissions overview style list of checkboxes would be easier to manage than a multi select element. So similarly to the other issue we could use that instead when chosen is not installed.

I'll try something

cool! make sure to check that the chosen module is not enabled for the checkbox UI.

Here is a first shot.

What I did:
- added a function to test if Chosen is active
- if not, change fields from select to checkboxes
- added a function to read values from form_state depending on field type (the array content is a bit different for checkboxes)
- added a bit of css to add an overflow and adjust display

Here is how it looks like :

It does not change a lot from the current version but checkboxes are still easier to use than ctrl + click.
I thought about adding a bit more interactivity in javascript (we could imagine showing selecting value in another div on the right for instance) but it feels like we are going to develop a brand new widget similar to Chosen. Probably not worth it, even if would be dependency free.

I fixed the width and height of the checkbox divs (400 x 300px). I wonder if there are responsive classes available for this in the backoffice theme.

Installed this patch and it is definitely much more intuitive than the multi-select list. Seems to work well.

One minor thing - the constants in here were switched from uppercase to lowercase, but the Drupal standard is to have them as all uppercase.

What about making the UI something like, "Select all except below " . One use case, I want to make a three split default, live and dev. Default will contain all the modules's config except some selected modules. So that I can ask my deploy team to drush csim default_config && drush csim live_config and can ask my developers team to use drush csim default_config && drush csim dev_config.

1. +++ b/src/Form/ConfigSplitEntityForm.php
   @@ -84,13 +84,18 @@ class ConfigSplitEntityForm extends EntityForm {
   +      '#multiple' => true,
   

   Don't break Drupal code style, please revert this change.

2. +++ b/src/Form/ConfigSplitEntityForm.php
   @@ -101,12 +106,12 @@ class ConfigSplitEntityForm extends EntityForm {
   +      '#multiple' => true,
   

   Same as above

3. +++ b/src/Form/ConfigSplitEntityForm.php
   @@ -114,13 +119,14 @@ class ConfigSplitEntityForm extends EntityForm {
   +      '#multiple' => true,
   

   Same as above

4. +++ b/src/Form/ConfigSplitEntityForm.php
   @@ -274,5 +320,4 @@ class ConfigSplitEntityForm extends EntityForm {
   -
   

   Please revert

Some of the points was lost in previous comment...

Please check test result page https://www.drupal.org/pift-ci-job/1007536 "14 coding standards messages, 14 more than branch result" means this patch introduced 14 new code style violations.

Re-rolling with capitalized `TRUE`.

Patch applied cleanly, and adds a checkbox next to all of the options as advertised.

Might want to lengthen the options boxes to make them wider, as sometimes when there is long config it wraps and breaks the flow of the checkmarks:

I have tested the patch in comment #13 running Drupal Core 8.7.5 and it works great! Thanks for making the patch!

Thank you all very much for your contribution!
I switched around a the css a bit and I added a variable for the multi select type and fixed coding standards. But it looks great now also without the chosen module.