I just found that deleting the component on PCB and click import changes will show up a "new" component with the modified package. But this is not a good way to do it (all the placement will be lost). Any better way known?

Hi, This is a well-know issue, but it is fixed, we will upload the new released next week. At present, you need to delete and import again.

Thx. Dillon! Puuuh... Not now, I go to bed.... BTW: Any script to check libraries and snap packages to the grid?

https://easyeda.com/Doc/Tutorial/API.htm#EasyEDA-API-Plug

I WANT ONE SILK LAYER ONLY BOTTOM?

I am not quite sure I understand your last question but if you only place components on the bottom layer then you will have a silk layer on only the bottom of the PCB.

Um, I have just checked the TO-220 package from the Through Hole Packages (under General Packages) in the left hand Navigation Panel and the pads are definitely exactly on a 100mil (0.1 inch) grid. Are you sure you have set your grid to 100mil? have you set it to mmm or have you left the Snap Size (snap to grid) at the defualt PCB setting of 10mil? If you have accidentally typed `G` then you may have toggled the snap to grid into the OFF state. Press `G` again to toggle it back on.

Doh! Useful as the advice that I just posted about correcting things being off-grid ago might be, it would help if I hadn't tried to answer an outdated question about something that was already fixed... ...and not made quite so many typos! :)