Dialog selection Criteria

I will assume you use the RunBase framework.

For the dialog part of your question see Axapta Dialog Validation.

To show the query dialog, you must provide two methods:

public boolean showQueryValues()
{
    return true;
}

and

public QueryRun queryRun()
{
    return queryRun;
}

The queryRun method must return a valid non-null value.

The queryRun instance variable is usually assigned a value in the unpack and initParmDefaultmethods.

Take a look on the CustInterestCancel class for a concise example.

How to disable the select button: return false from showQueryValues.