I recently experienced this issue in ECC 5.0 as well, after a client's support pack upgrade. In our case, we decided to switch it back as our form developers were getting various Visual Basic pop-up error messages while using the new MS Word editor (e.g. "Code execution has been interrupted").
Here are the instructions we followed from SAP on how to switch it back. Note that this is a global switch (it will impact everyone):
"Call transaction se38, enter program RSCPINST or program RSCPSETEDITOR and press Execute (F8). On the next screen, select Goto -> Set MS Word as Editor. When the checkbox is selected, deselect checkbox SAPscript/ Smart Forms and press 'Activate'. When it is not selected, simply press 'Activate'."
Once you have done the above, completely leave the Smart Forms transaction and then re-enter it. You should now see the earlier editor again, with all its icons intact.
For earlier releases the steps above might be slightly different. This is all documented in SAP Note 791199 ("Default editor changed to MS Word in SAPscript and Smart Forms").
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