Add possibility to PreSet filter to defined custom dashboard which affects widgets with dynamic item. It should be like ADD_URL_parameter, added to call string URL with dashboardID=nn .
It could be defined in Dashboard properties window.
Only defined filter parameters should be added to call URL.
For bypass of this I used simple small 1 item map widget with popup list of URLs of custom dashboards where I can set this filter, but it is not user friendly and also it missing dynamic changes of source list of dashboards.
1.Add column(s) to table of dashboards - groupid,hostid (or string for URL&add)
2.Add to Form Dashboard properties textbox for URL&add or Group Host combobox picker (like here in attachment)
3.Modify Dashboards form (dashboard.list) to compose all dashboards URL with addition of only defined filters for dashboards widgets (with checked Dynamic item)