We need to nsTextFrame chain for bug 164700, bug bug 156369, bug 289130 and bug 288439. Because these bug needs the first character of next frame or last character of previous frame. Currently, we have mNextInFlow. But it cannot solve to the follwing case. A<span style="position: absolute; top: 500px;">B</span>C In this case, the mNextInFlow is null. But, for rendering, we need to get C in A.

Isn't there already some code in nsTextFrame to find the next frame? (Which might not be a text frame --- it could be any inline frame.)

Roc: Really? Can we get the next (any) frame from nsTextFrame? I think that we can get the next frame only after all text frame's reflow. Therefore, I think that I will create the chain at nsBlockFrame::PlaceLine, like TrimTrailingWhiteSpace.

GetNextSibling()

GetNextSibling is not related the line layout. e.g., the end of line frame's GetNextSibling returns not null.

nsLineLayout::FindNextText() we use that for, e.g., <a>x&nbsp;</a><b>y</b>. In this case, "x y" has to be measured as a single non-breakable unit to see if it fits. (It has sufficently matured and is robust enough to deal with all sorts of nesting.) As this kind of information is needed at reflow, it is okay to assume that a linelayout object will be there. Then, at paint, it is assumed that whatever has been flagged at reflow can be recovered (like trimming spaces or ignoring parts of the text).