Hi Konstantin,
If you want to disable the toolbaar buttons of each assignment block, then you need to do the code changes in each assignment block's (View's) do_prepare_output method.
Acutally there is a global table gt_button_header, in the impl class of respective view. U need to read that table and change the "enabled" value of particular button to 'false'. after these changes the corresponding button will remain grayed out based on your condition.
e.g.
***************** Title toolbar *****************
IF gt_button_header IS INITIAL.
ls_button-text = cl_wd_utilities=>get_otr_text_by_alias( 'CRM_UIU_BP/BP_EDITLIST' ). "#EC NOTEXT
ls_button-on_click = 'editlist'. "#EC NOTEXT
APPEND ls_button TO gt_button_header.
CLEAR ls_button.
ENDIF.
* set button status
ls_button-enabled = lv_display_mode.
MODIFY gt_button_header FROM ls_button TRANSPORTING enabled
WHERE enabled NE ls_button-enabled.
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