From Unofficial BOINC Wiki
Beginning with Version 5.8.0 the BOINC Manager has two faces. The Advanced View that has been around for some time and the new Simple View. (Open it by clicking "View" -> "Simple View" in the menubar, switch back by clicking button "Advanced View")
The styles of this Simple View are changeable with BOINC Skins. Projects, Participants and Teams may create and share BOINC Skins. The BOINC Skin consists of a file named "skins.xml" and several graphic files, they are all stored in a folder under the skins folder in the BOINC folder. To change the view to another installed BOINC Skin, open the Simple View, click on button "Preferences", choose another BOINC Skin in the menu and click on the "Save" button.
 External BOINC skin Resources
 Install BOINC Skins
Each BOINC Skin is in it's own skin folder stored in a BOINC sub-folder called "skins". If one does not exist yet please create it manually and copy the skin folder into it. For example "C:\Program Files\BOINC\skins\skinfolder" on Windows.
 Create BOINC Skins
A BOINC Skin is a folder including a file "skins.xml" and graphic files, this includes all the graphics/icons belonging to the skin.
The skin.xml file stores all the skin name, graphic names, the button- and icon names, link URLs, line and registry tab colors and their relationship to the skin. Just change an existing, or create a new one.
The following Graphics are needed in exact sizes:
- background_image - 540px x 410px. Simple GUI background image.
- spacer_image - 11px x 2px. Separate the links on the bottom of the Simple GUI.
- state_indicator_background_image - 35px x 264px.
- connecting_indicator_image - 15px x 14px.
- error_indicator_image - 20px x 69px.
- workunit_tab_area_background_image - 24px x 343px.
- workunit_area_background_image - 314px x 343px.
- workunit_animation_background_image - 146px x 294px.
- workunit_animation_image - 126px x 290px.
- workunit_gauge_background_image - 18px x 258px.
- workunit_gauge_progress_indicator_image - 7px x 8px.
- project_area_background_image - 113px x 343px.
- project_image - 40px x 40px. Default image to display for a project that does not currently have an image defined.
- attach_project_button - 18px x 81px.
- right_arrow_button - 20px x 20px.
- left_arrow_button - 20px x 20px.
- save_button - 16px x 57px.
- cancel_button - 16px x 57px.
- close_button - 16px x 57px.
- copy_all_button - 18px x 85px.
- copy_button - 18px x 85px.
- messages_link_image - 20px x 70px.
- messages_alert_link_image - 20px x 70px.
- suspend_link_image - 20px x 59px.
- resume_link_image - 20px x 59px.
- preferences_link_image - 20px x 81px.
- advanced_link_image - 20px x 101px.
- dialog_background_image - 600px x 800px.
- help_button - 18px x 18px.
All graphics are in a strict relationship to the main skin background image!
An easy way to cut them from the background_image exactly is to use templates. You can download templates.
The standard graphic format is *.png, but it's possible to use some others (jpg, gif ... ), but take care to include the description in skin.xml also!