You may also invoke the text editor in what appears to be a standalone window, almost as if it was an independent application (with its own title bar and menu). To do this, set the TXF_POPUP bit in the flags parameter (and set the TXC.PARENTID field to a suitable parent control.) As with other control/window arrangements, set the coordinates relative to the grid system of parent window, although once the control is displayed, the user will be able to move and resize it, almost as if it were independent of the application (except that it will still act like a modal dialog.)
Note that as of build 953.3 you can specify the coordinates in absolute pixels by setting the srow, scol, erow and ecol parameters to the negative of the desired pixel coordinates. In that case, the TXC.PARENTID wo not affect the positioning, but it will still affect the "z-order" and the ownership of the popup XTEXT window. (For example, if you specify the parent ID of the current dialog, then the XTEXT popup window will be automatically deleted when the dialog is deleted, whereas if you set TXC.PARENTID to 0, the popup XTEXT window will not be affected by deletion of the current dialog.)