Order View page add custom button using Events

[admin123]

I have uses "adminhtml_block_html_before" events to add button in order view page.
I have print button list in tohtlm I got my custom button there but in backend It not displayed.

[admin123]

Please give me some solution, is It bug ?

[Stuperfied]

Please be patient, developers here are very busy and don't have time to troubleshoot possible errors when there are so many confirmed actual errors to be fixed. Sorry for being blunt but this section is for you to tell developers about bugs, not get help with your code. If you are in a hurry, please use a 3rd party source such as the magento section in stack exchange and report back here if you can confirm it is a bug.

[daim2k5]

The GitHub issue tracker is intended for technical issues only. Please refer to the Community Forums or Magento Stack Exchange site for technical questions. In your case, the programming questions forum is likely the most appropriate. Feel free to reopen this issue if you think you have encountered a bug in Magento 2.