Thanks for looking into this.
I'm still using Delphi 7. Not going to move to BDS for some time. 
But what is the problem with virtual tree? 
I seem to remember that they used Mike Lischkes virtual string tree (
http://www.lischke-online.de/VirtualTreeview/) in many places (project manager, structure pane, message view, refactoring window). 
I'm somewhat familiar with the component. TBaseVirtualTree.GetSortedSelection will return all selected nodes. 
It returns a TNodeArray. 
TNodeArray = array of PVirtualNode; 
PVirtualNode = ^TVirtualNode;
TVirtualNode = packed record
    Index,                   // index of node with regard to its parent
    ChildCount: Cardinal;    // number of child nodes
    NodeHeight: Word;        // height in pixels
    States: TVirtualNodeStates; // states describing various properties of the node (expanded, initialized etc.)
    Align: Byte;             // line/button alignment
    CheckState: TCheckState; // indicates the current check state (e.g. checked, pressed etc.)
    CheckType: TCheckType;   // indicates which check type shall be used for this node
    Dummy: Byte;             // dummy value to fill DWORD boundary 
    TotalCount,              // sum of this node, all of its child nodes and their child nodes etc.
    TotalHeight: Cardinal;   // height in pixels this node covers on screen including the height of all of its
                             // children
    // Note: Some copy routines require that all pointers (as well as the data area) in a node are
    //       located at the end of the node! Hence if you want to add new member fields (except pointers to internal
    //       data) then put them before field Parent.
    Parent,                  // reference to the node's parent (for the root this contains the treeview)
    PrevSibling,             // link to the node's previous sibling or nil if it is the first node
    NextSibling,             // link to the node's next sibling or nil if it is the last node
    FirstChild,              // link to the node's first child...
    LastChild: PVirtualNode; // link to the node's last child...
    Data: record end;        // this is a placeholder, each node gets extra data determined by NodeDataSize
  end;
Hope that helps!