That looks like a bug. In the tag_select_match function in taggui.e, if you change the code to this, the problem appears to go away. I removed SL_XY_WIDTH_HEIGHT from the list of masks. I don't know if this will cause other problems so be prepared to revert the change if you try it. Load the module using the "load module" command in the macro menu.
match_id = select_tree(captions, match_ids, pictures, overlays,
null, tag_select_callback, null,
"Select Symbol",
SL_COLWIDTH|SL_SIZABLE|SL_USE_OVERLAYS,
"Name,File,Line,",
columnInfo,
true,
"Select Symbol dialog",
"find_tag"
);