Version:            (using KDE KDE 3.3.2)
Installed from:    Unspecified
OS:                Irix

To reproduce:

Open four konsoles on one desktop. Have the left and right top two konsoles overlap their right and left sides respectively.  Repeat this for the bottom two konsoles. Position two of the konsoles such that neither konsole touches the other two konsoles. With 'Focus follows mouse' turned on, position your mouse cursor on a portion of one of the konsoles that does not overlap another konsole.  Alt-tab should cycle through all konsoles as expected. Good!  Now, move your mouse cursor such that it hovers over one of overlapping portions of the konsole.  Pressing alt-tab now results in one of the windows being skipped--ie, impossible to reach with alt-tab.  It appears that focus is given to the window very briefly, but then stolen.   

Terrible ascii art:
  v-v- overlap
--- ---  <- konsole terminals
--- x-o  <- konsole terminals
  ^-^-   overlap

x marks the point of overlap over which the mouse hovers between the two konsoles that results in the skipping of the konsole when alt-tab is used to traverse.  The non-overlapping position marked by the 'o' over which the mouse hovers gives the correct behavior.