Re: address@hidden: enlarge-window with preserve-before non-nil]

[Richard Stallman]

    I looked a bit, but I am not sure how it shall work.  If I just to three 
    windows, in the obvious way (C-x 2, C-x 2), I get three windows, one 11 
    lines, one 12 lines and one 24 lines.  This gives me this window 
    configuration:

    0x86b6b10: vchild: 0x861d830, hchild: 0x0, next: 0x861d9c8, parent: 0x0, 
    h: 47
    0x861d830: vchild: 0x0, hchild: 0x0, next: 0x8694a50, parent: 0x86b6b10, 
    h: 11
    0x8694a50: vchild: 0x0, hchild: 0x0, next: 0x86b6ca8, parent: 0x86b6b10, 
    h: 12
    0x86b6ca8: vchild: 0x0, hchild: 0x0, next: 0x0, parent: 0x86b6b10, h: 24
    0x861d9c8: vchild: 0x0, hchild: 0x0, next: 0x0, parent: 0x0, h: 1

That's the correct configuration for such a case.


    But if I create the same three windows (11, 12 and 24 lines) with the 
    method below, I get this window configuration:

    0x8833558: vchild: 0x87f9978, hchild: 0x0, next: 0x861d9c8, parent: 0x0, 
    h: 47
    0x87f9978: vchild: 0x86a7a48, hchild: 0x0, next: 0x8820a48, parent: 
    0x8833558, h: 23
    0x86a7a48: vchild: 0x0, hchild: 0x0, next: 0x87b6d68, parent: 0x87f9978, 
    h: 11
    0x87b6d68: vchild: 0x0, hchild: 0x0, next: 0x0, parent: 0x87f9978, h: 12
    0x8820a48: vchild: 0x0, hchild: 0x0, next: 0x0, parent: 0x8833558, h: 24
    0x861d9c8: vchild: 0x0, hchild: 0x0, next: 0x0, parent: 0x0, h: 1

This is a bug.  A window which is a vchild should never have a vchild.

Can you determine at which step the structure first becomes
incorrect?  That is where the bug is, I think.