To load tpl file on dropdown change you need xajax function which will do this.
You can do xajax function based on other functions in the script. there are just few mandatory things to make it working properly
1. Create function somewhere in the class file. for example in the rlCategories.class.php
PHP Code:
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2. Register function in the place you need it. if you want your maps on home page only than right place is controllers/home.inc.php
PHP Code:
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3. use it in the javascript like below
Code:
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It's not ready instruction and just some detailed thoughts about xajax and how this can be done.