When you mouse down on a treecell header, since it looks like a button it should behave like a button. I have already got a fix for this on windows classic.

Some notes about the patch I'm about to submit: In addition to making treecell headers clickable, I had to make some other changes around the theme to adjust to the new headers. Specifically, I changed the way tree focus rings look in messenger, and tweaked treerow focus borders and removed some crud from editor. The forthcoming patch fixes both modern and classic win.

This patch can't go in (as is) until the patch for bug 57429 is checked in. I need to take a closer look (maybe later), but one thing which stood out was this: +tree:focus > treechildren treeitem[selected="true"][current="true"] > treerow, +tree:focus > treechildren treeitem[selected="true"][current="true"] > treerow > treecell { Do you need the descendant selector here or could you get away with some child selectors?

You're right -- those descendant selectors are nasty. They have been there since before we shipped NS6. The problem is that only the tree receives focus, not individual treerows. If we want to optimize this, we should write some code in the tree xbl binding which marks the selected rows with a "focused" attribute whenever the tree is focused. I'll file that issue as a separate bug -- for now, let those descendant selectors stay in there, they are needed because treeitems can be nested at any depth within trees.

Why does modern need its own tree header XBL bindings? Would these be more appropriately placed in treeBindings.xml where all skins could use them, or are they really skin specific?

You're right, I should probably put those in treeBindings.xml. The reason I did it that way is because I simply copied those bindings from the classic skin, but they should probably be dumped from classic and shared. Will submit adjusted patch shortly.

Actually classic needs its own content bindings at least because classic treeheaders have multilevel borders, at least on Windows.

(unless you plan to have an extra box in the global binding as well)

Might as well have the extra box in the global content binding. All of our skins now use it, and it's one less thing for a theme author to have to worry about. I'm also moving the treecell-header-image binding into global/content/treeBindings.xml

fixed

Marking verified (2001-02-21-04-Mtrunk).