I noticed the d key deleting a line on a single press as well. I am using Spacemacs [email protected] on the develop branch. I do not know if this is your case, but I had an incomplete search in progress.

Steps to reproduce:

1. In command mode, initiate a search by pressing the / key
2. With the mouse, click on any text in your buffer
3. Press the d key a single time and a line will be deleted

Steps to resolve:

1. With the mouse, click on your incomplete search
2. Either cancel the search by pressing the DEL key until the search is cleared OR complete the search by pressing the RET key
3. The behavior of the d key should return to normal (at least it did for me)

I noticed the d key deleting a line on a single press as well. I am using Spacemacs [email protected] on the develop branch. I do not know if this is your case, but I had an incomplete search in progress.

Steps to reproduce:

1. In command mode, initiate a search by pressing the / key
2. With the mouse, click on any text in your buffer
3. Press the d key a single time and a line will be deleted

Steps to resolve:

1. With the mouse, click on your incomplete search
2. Either cancel the search by pressing the DEL key until the search is cleared OR complete the search by pressing the RET key
3. The behavior of the d key should return to normal (at least it did for me)

Update 2019-05-14
I stumbled upon a solution from @trey-jackson. For spacemacs users, plunking Trey's solution:

(defun stop-using-minibuffer ()
    "kill the minibuffer"
    (when (and (>= (recursion-depth) 1) (active-minibuffer-window))
      (abort-recursive-edit)))

(add-hook 'mouse-leave-buffer-hook 'stop-using-minibuffer)

in .spacemacs under dotspacemacs/user-config seems to resolve the problem.

I noticed the d key deleting a line on a single press as well. I am using Spacemacs [email protected] on the develop branch. I do not know if this is your case, but I had an incomplete search in progress.

Steps to reproduce:

1. In command mode, initiate a search by pressing the / key
2. With the mouse, click on any text in your buffer
3. Press the d key a single time and a line will be deleted

Steps to resolve:

1. With the mouse, click on your incomplete search
2. Either cancel the search by pressing the Backspace key until the search is cleared OR complete the search by pressing the Enter key
3. The behavior of the d key should return to normal (at least it did for me)

I noticed the d key deleting a line on a single press as well. I am using Spacemacs [email protected] on the develop branch. I do not know if this is your case, but I had an incomplete search in progress.

Steps to reproduce:

1. In command mode, initiate a search by pressing the / key
2. With the mouse, click on any text in your buffer
3. Press the d key a single time and a line will be deleted

Steps to resolve:

1. With the mouse, click on your incomplete search
2. Either cancel the search by pressing the DEL key until the search is cleared OR complete the search by pressing the RET key
3. The behavior of the d key should return to normal (at least it did for me)