How could I open in new window/tab/buf when jump to define(gD)

[x2c3z4]

When using 'jump to define', the new file always replace the original file buffer.

[adoyle-h]

Just type gd to open float window to query the definition of the symbol under the cursor.

By the way, in float window, you can type <C-w>t to turn current window into a new tab.

Please see keymaps.md.