Issue #3124010 by david.czinege: Fix the thead style issue, when user updates an exisiting table.
requested to merge issue/ckeditor_bootstrap_table-3117068:3117068-fix-thead-styles-for-exisiting-tables into 8.x-1.x
I have fixed the Headers style (thead) issue.
The Headers style field only works, when the user creates a new table. If the user want to update an already existing table (right click on the table and select the Table Properties option), the Headers style field is always empty in the CKEditor dialog. If the user changes it to Light theme or Dark theme, nothing happens.
I have fixed these two issues, so when the user updates an exisiting table, the Headers style field shows the actual theme of the table, and if the user changes it, the table's thead HTML element will get the appropriate class.