168326 - Rework the preference stylesheet

Status: RESOLVED WORKSFORME

(Core :: Layout, defect, P3)

Description

[Boris Zbarsky [:bzbarsky]]

The preference stylesheet has several issues in how its handled. The upshot is
that we have to do a lot more work than we should have to when a preference
changes.  Basically, we rebuild the whole sheet when any preference changes (we
should just poke the corresponding rule.

A simple patch that speeds up changing appearance prefs a lot without actually
addressing the underlying problem is:

-      ReconstructFrames();
+      //ReconstructFrames();
+      ReconstructStyleData(PR_TRUE);

in the presshell's SetPreferenceStyleRules

Comment 1

[Boris Zbarsky [:bzbarsky]]

It looks like nsIPresShell::EnablePrefStyleRules and
nsIPresShell::ArePrefStyleRulesEnabled are basically unused.  They are there for
use by Editor, in theory (though they don't really work).

Would anyone object to me just removing them?

Comment 2

[Robert O'Callahan (:roc) (email my personal email if necessary)]

I don't object, but I don't know anything about the editor...

Comment 3

[Daniel Glazman (:glazou) (not active in Mozilla any more)]

I have no idea why the editor uses it. We should ping Kin or Simon.

Comment 4

[Boris Zbarsky [:bzbarsky]]

Maybe I wasn't clear... Editor does NOT use them.  The checkin comment that
added them says they are "for use by editor".  The only question I have is
whether editor has plans to use these in the future.

Comment 5

[Simon Fraser [no longer active]]

I think they are obsolete; maybe cmanske had plans for them, but if Daniel
doesn't need them now, then let's nuke 'em.

Comment 6

[Boris Zbarsky [:bzbarsky]]

We no longer unconditionally reconstruct when preference rules change (we RebuildAllStyleData instead, and do whatever that means hint-wise), and we now have a single shared preference sheet, so the "rebuild it from scratch" is a much smaller issue. Going to mark this worksforme.