iMouse.w behavior is different from Shadertoy

[theetcher]

I assume this "desync" happened in Nov, 2020

from https://shadertoyunofficial.wordpress.com/2016/07/20/special-shadertoy-features/

mouse button events ( added in Nov, 2020 ):

• down even (i.e. just clicked) if iMouse.z > 0. && iMouse.w > 0.
• currently down: if iMouse.z > 0. ( && iMouse.w < 0.)
• released: if Mouse.z < 0 && iMouse.w < 0.

It is more clearer if you observe this shader for iMouse channels data in the left-bottom corner: https://www.shadertoy.com/view/llySRh

in short - sign management is different:

• iMouse.w:
  • positive only for the first frame if mouse button pressed
  • otherwise it is negative