Default full screen caller

hi, im in 4.4.2 kitkat slimkat 5.4 on y300 huawei, but that rom dont have full screen caller, its have that black things ish...

im already use gravity box exposed, its worked, but that gravity box it messing with my setting, clock, navigation bar and lot more... so im asking, can i make fullscreen caller without gravitybox? can anybody teach me to edit file or something.. please help... :3