An alternative to store key-value paired properties in appSettings in web.config we can use Sharepoint_config database by creating our own SPPersistedObject.  First we have to create a class which inherits from SPPersistedObject and decorate its properties with [Persisted]:

namespace Takana.SharePoint
{
    public class Settings: SPPersistedObject
    {
        \[Persisted\]
        public string DbConString;
 
        public LinkCheckerPersistedSettings() { }
        public LinkCheckerPersistedSettings(string name, SPPersistedObject parent) : base(name, parent) { }
    }
}
```Then we must create such an object. Let's do it in Powershell:

if(-not(Get-PSSnapin | Where { $_.Name -eq “Microsoft.SharePoint.PowerShell”})) { Add-PSSnapin Microsoft.SharePoint.PowerShell }

Now a user can choose what to see on the map. Maybe only bike pumps or everything. To do that I created a new class ListPreferenceMultiSelect extends ListPreference which is more or less taken from DroidWeb tutorial. The source ListPreferenceMultiSelect.java was improved a little bit: The constructor checks if entries are not empty before creating indices. For the second a new method was added: prepareValueToStore, the opposite one of parseStoredValue. Here is my ListPreferenceMultiSelect.java and in the version 0.2.6. This version was published on the Market and committed to the repository.