Product Version = NetBeans IDE 8.2 (Build 201609300101)
Operating System = Linux version 4.7.6-200.fc24.x86_64 running on amd64
Java; VM; Vendor = 1.8.0_101
Runtime = Java HotSpot(TM) 64-Bit Server VM 25.101-b13

Reproducibility: Happens every time

STEPS:
  * writing some PHP code, a function call like:

    // Updating the image value..
    ImageUtil::updateImgFieldValue(

  * when I open the parenthesis  "(", the function signature tooltip appears like in the picture attached 
  * however, the signature tooltip doesn't stick and randomly disappears
  * for example if I start to type a litteral as second parameter..

    // Updating the image name..
    ImageUtil::updateImgFieldValue($ID, "s
   
    the signature tooltip disappears.

  * writing some Javascript code, a function call like:
    
    saveChanges(
 
    where the function is also well documented.

  * the signature tooltip doesn't work 

     
ACTUAL:
  PHP: the function signature tooltip doesn't stick, sometimes disappears.
  Javascript: the signature tooltip doesn't work 

EXPECTED:
  PHP: the function signature tooltip appears and sticks
  Javascript: the signature tooltip appears and sticks