SharePoint Tool Pane, where are you?

A colleague of mine are creating a new master page for an ECM site. Once all SharePoint controls were included into the new master page, we found that the tool pane (the one that shows web part properties) went off the grid, not restricted by the boundary of HTML tables etc.

After some research, it is concluded that the mater page need to include a PlaceHolder tag with an ID of “MSO_ContentDiv”. Followed by the PlaceHolder is a HTML table tag with an id of “MSO_ContentTable”. Both of these tags can be found in OOB SharePoint master pages. Once these two tags are in place, the tool pane attaches itself to the left side of this HTML table when it is summoned.