Dear Visual FoxPro users

In some cases when I do a setfocus to a control, the control generates
a lostfocus(I don't know why). I have been fighting this problem for
a while! Today I converted my project from 3.0b to 5.0 to test if the
problem still existed. The problem didn't exist in 5.0, so my
question is: can I assume it is a bug somewhere in VFP 3.0b