Why create cdrom drive is greyed out in virtualbox

Cdrom drive can be added only if the machine is shut down, not saved.

Virtual machine: Preconfigured LAMP stack with php 7

1. Install virtualbox: https://www.virtualbox.org/

2. Download the first VM build which works with virtualbox: https://www.turnkeylinux.org/lampstack

3. Import it into virtualbox. This gives us a LAMP stack with php 5.0

4. Install php7 in the VM: https://shiji.info/blog/2016/en/99

5. disable php5:  a2dismod php5

6. enable php7: a2enmod php7.0

7. restart web server

Exlamaction mark next to wifi icon on android

It indicates the phone cannot connect google servers. A reboot usually solves this if the problem persists.

How to search for images by color

Sometimes when you search for an image you want to see only matches of specific color. Here's a trick to do it with Google Image Search. Search for an image then add this to the link to search, for example, green images:

&imgcolor=green

RSS feed URL for Youtube channels

So Youtube doesn't provide this anymore on the web interface, but this seems to work:

https://gdata.youtube.com/feeds/api/users/channelname/uploads?v=2&alt=rss

Just replace channelname with the name of the channel you want to subscribe to via RSS.

How to unstick the stuck Control key on Windows

Sometimes on my Windows 7 out of the blue the control key becomes stuck, that is the computer behaves like the control key was pressed all the time. It is really annoying, but there is a simple trick to cure it. Just press the control, alt and shift keys on the left side of keyboard, one after the other, then press these keys on the right side one after the other. This usually solves the problem for me.

How to clear the DNS cache of Opera

I didn't find an easy way to do it, but restarting the browser seems to do the trick.