I found something similar..
Open in online IDE; Here is a strange Blitz3D bug. Tested with 1.88, probably affects all versions. ; This should fill the screen with random dots. ; But after a few seconds a pattern begins to emerge. magic = -412005 ; Incredibly, -412005 is the one number which shows the bug. Graphics 640, 480, 0, 1 :f=LoadFont(" ",72):SetFont f:img=CreateImage(320,120):ib=ImageBuffer(img):SetBuffer ib:Text 12,24,"DarkBasic" SetBuffer FrontBuffer() SeedRnd magic Repeat r = Rand(50,150) : g = Rand(50,150) : b = Rand(50,150) x = Rand(0,640) : y = Rand(0,480) If magic=-412005 Then If ReadPixel(x Mod 320 ,y Mod 120,ib) And $FF Then r=r-50:g=g-50:b=b-50 Color r,g,b : Plot x,y n = n + 1 : If (n Mod 10)=0 Then Delay 1 Until KeyDown(1)