Default Verb (Edit Web part and minimize) are missing in BrowseDisplayMode when there is no custom verb added

Hi there,

i have created a few custom web parts here, i found that the minimize and edit web part verb will be visible in BrowseDisplayMode if there is custom verb added.
For those web parts without the custom verb, these 2 context menu items will be visible in Edit mode only but not the BrowseDisplayMode.

My question is how can i make those default verbs being visible in BrowseDisplayMode when there is no custom verb added for a web part?

Thanks!