PHP breadcrumb class
You are not always returning anything

private function checkUrlAction($sAction) {
    if(true){         
        return true;
    }

    //but else?
}


Dependency injection

$objShowPDO = new mShowPDO(); is bad a mShowPDO instance should by injected via method or constructor argument see dependency injection topics

private function checkUrlItem(mShowPDO $objShowPDO, $sItem){
    if($sItem == 'imagelist' || $sItem == 'mkdir' || $sItem == 'rdir'){
        return true;
    }

    //redundand else removed

    $result = $objShowPDO-&gt;allTables(); //maybe you can inject only the result
    while($array = $result-&gt;fetch()){
        if($array[0] == $this-&gt;sItem){
            return true;
        }
    }

    return false;
}


Hard coding

The checklists are really hard coded (long if with OR relations), try use some container for them (an array and use in_array() for example).