Summary

Adds DandersFrames (CurseForge) as a selectable anchor parent in the custom viewer categories, so users can anchor BCDM bars (Custom / Additional Custom / Item / Items-Spells / Trinket) to their party/raid unit frames.

Changes

Core/Globals.lua

Added two anchor keys to the BCDM.AnchorParents table for the 5 custom viewer categories (Custom, AdditionalCustom, Item, Trinket, ItemSpell):

• DandersPartyHeader — the party SecureGroupHeaderTemplate frame (auto-sized to the visible party frames).
• DandersRaidFramesContainer — the raid container frame.

Both frames are top-level globals created by DandersFrames, so they resolve through the existing _G[Layout[2]] lookup with no additional load-order requirements. If DandersFrames isn't installed, the option is still shown but falls back to UIParent (see below).

CustomViewers/*.lua (5 files)

Two small robustness fixes applied uniformly to every anchorParent resolution site:

1. or UIParent fallback — if the saved anchor key refers to a frame that no longer exists (e.g. user disabled the anchor addon), _G[key] returns nil; falling back to UIParent avoids SetParent(nil) / SetPoint(..., nil, ...) errors.

2. container:SetParent(anchorParent) added next to each container:SetPoint(..., anchorParent, ...) call for the 5 viewer containers (CustomCooldownViewer, AdditionalCustomCooldownViewer, CustomItemBar, CustomItemSpellBar, TrinketBar).

   Re-parenting makes the BCDM container inherit visibility from the anchor. This is necessary for DandersFrames (the raid container is hidden in party mode and vice-versa), and it also aligns behavior with other addons that hide their frames conditionally. Icons previously remained visible in their old position even when the anchor frame was hidden.

Testing

• Anchored the Custom bar to DandersFrames: Party Header / DandersFrames: Raid Container and verified it tracks the frames and hides together with them when switching DandersFrames profiles between party and raid modes.
• Verified existing anchors (UIParent, PlayerFrame, TargetFrame, other BCDM bars, ElvUI frames) still work unchanged.
• Verified no errors when switching profiles to one that references a missing anchor.

Notes

• No new dependencies. DandersFrames is optional — if it's not installed, the options simply fall back to UIParent.
• No saved-variable migration needed; this only adds new entries to the dropdown list.