In PhpStorm, when you double click on a variable, say $_helloWorld, it just selects a part of the variable. For example, when you double click on World
$_helloWorld
World
Super late answer, haha, but here is the exact option to enable selecting $ in variable names:
$
File | Settings | Editor | General | Smart Keys | Select variable name without '$' sign on double click
Should be disabled.
disabled