1) How did you install dragmath? Did you follow the instructions in the moodle docs? Did you edit or replace adminlib.php
2) If you look at the CVS of the dragmath install you will note that Dragmath itself is contained in a /plugins/DragMath folder that is placed in /lib/editor/htmlarea - other than that there are just a few files that are involved, including dialog.js, htmlarea.php, /popups/dlg_ins_dragmath.php and images/em.icon.dragmath.gif .
3) Probloems typically arise with the CVS install because you are overwriting instead of patching htmlarea.php and dialog.js when you install dragmath, or when you install another editor module that then overwrites the htmlarea.php and dialog.js files you installed with DragMath. Since these files should be backed up before install, replacing these files should resolve all editor problems associated with DragMath. This is one downside of providing DragMath in this manner. As mentioned elsewhere it should be fairly simply to compare the two files in question and resolve the conflicts.
4) adminlib.php seems subject to rather regular modification, so in order to avoid unpleasant consequences, the docs indicate that this file should not be replaced but the file edited instead. If you installed the adminlib.php that is packaged with dragmath and then upgraded to 1.9.2 you should not lose dragmath functionality (see comments on this in the moodle docs) but if you then write the adminlib from the dragmath zip back to your installation I do undersdtand that this causes loss of functionality
