[zork]

I reviewed my code.

Now we have a dedicated dragframe that sits on top of the anchored frame.
The dragframe receives the drag event and delegates the mouse move event to the anchored frame.

Additionally lock/unlock and reset function can be anchored directly on the frame.

--apply drag functionality to any frame
  local applyDragFunctionality = function(self)
    --save the default position
    local getPoint = function(self)
      local pos = {}
      pos.a1, pos.af, pos.a2, pos.x, pos.y = self:GetPoint()
      if pos.af and pos.af:GetName() then pos.af = pos.af:GetName() end
      return pos
    end
    self.defaultPosition = getPoint(self)
    --the drag frame
    local df = CreateFrame("Frame",nil,self)
    df:SetAllPoints(self)
    df:SetFrameStrata("HIGH")
    df:SetHitRectInsets(0,0,0,0)
    df:SetScript("OnDragStart", function(self) if IsAltKeyDown() and IsShiftKeyDown() then self:GetParent():StartMoving() end end)
    df:SetScript("OnDragStop", function(self) self:GetParent():StopMovingOrSizing() end)
    --dragframe texture
    local t = df:CreateTexture(nil,"OVERLAY",nil,6)
    t:SetAllPoints(df)
    t:SetTexture(0,1,0)
    t:SetAlpha(0.2)
    --stuff
    df.texture = t
    df:Hide()
    self.dragframe = df
    self:SetClampedToScreen(true)
    self:SetMovable(true)
    self:SetUserPlaced(true)
    --helper functions
    --unlock
    local unlock = function(self)
      if not self:IsUserPlaced() then return end
      self.dragframe:Show()
      self.dragframe:EnableMouse(true)
      self.dragframe:RegisterForDrag("LeftButton")
      self.dragframe:SetScript("OnEnter", function(self)
        GameTooltip:SetOwner(self, "ANCHOR_TOP")
        GameTooltip:AddLine(self:GetParent():GetName(), 0, 1, 0.5, 1, 1, 1)
        GameTooltip:AddLine("Hold down ALT+SHIFT to drag!", 1, 1, 1, 1, 1, 1)
        GameTooltip:Show()
      end)
      self.dragframe:SetScript("OnLeave", function() GameTooltip:Hide() end)
    end
    --lock
    local lock = function(self)
      if not self:IsUserPlaced() then return end
      self.dragframe:Hide()
      self.dragframe:EnableMouse(false)
      self.dragframe:RegisterForDrag(nil)
      self.dragframe:SetScript("OnEnter", nil)
      self.dragframe:SetScript("OnLeave", nil)
    end
    --reset position
    local reset = function(self)
      if self.defaultPosition then
        self:ClearAllPoints()
        local pos = self.defaultPosition
        if pos.af and pos.a2 then
          self:SetPoint(pos.a1 or "CENTER", pos.af, pos.a2, pos.x or 0, pos.y or 0)
        elseif pos.af then
          self:SetPoint(pos.a1 or "CENTER", pos.af, pos.x or 0, pos.y or 0)
        else
          self:SetPoint(pos.a1 or "CENTER", pos.x or 0, pos.y or 0)
        end
      else
        self:SetPoint("CENTER",0,0)
      end
    end
    self.unlock = unlock
    self.lock = lock
    self.reset = reset
  end

If you want to call the function you can make use of the global frame name and slash commands.

--CALL
 
    local function SlashCmd(cmd)
    if (cmd:match"unlock") then
      myFrame.unlock(myFrame)
    elseif (cmd:match"lock") then
      myFrame.lock(myFrame)
    elseif (cmd:match"reset") then
      myFrame.reset(myFrame)
    end
  end
 
  SlashCmdList["mymod"] = SlashCmd;
  SLASH_mymod1 = "/mymod";

The most important part is that the drag function gets called on code init. It must not be called on events like PLAYER_LOGIN. That will reset the values that Blizzard read from the layout-local.txt file.

Example implementations:
http://code.google.com/p/rothui/source/detail?r=841