What is foo_looks?
It's a plugin for foobar2000, developed by DanZ. Its previous name was foo_WSGUI.
It allows the use of "skins", called LOOKS by convention (you know, skins for Winamp, Looks for foobar).
It's intended as a complement for the standard foobar UI, that remains as the best playlist we can have (IMHO). But for some users could be a full alternative.

How must I install it?
Just download foo_looks.zip from here or from www.foobarlooks.tk, and unzip the files in the "components" folder (inside of the foobar2000 folder).
Now, you must have:
-foo_looks.dll
-foo_looks folder, with a few graphics and *.ski files
These are the "standard" Looks. If you want to add new Looks, you must copy their files to the foo_looks folder.

Design of Looks

/////////////////////////////////////////////////////////////////////
// USER DEFINED COLORS (More usual colors - Optional)
/////////////////////////////////////////////////////////////////////
section color
list black int { 255 5 5 5 }  // Alpha Red Green Blue
list white int { 255 255 255 255 }
list lcd int { 255 216 216 204 }
list transparent int { 0 0 255 0 } // The easiest way is to fill the transparent zones with a "pure color" and define it as transparent. So the pure green (0 255 0) will be transparent in our graphic.

/////////////////////////////////////////////////////////////////////
// WINDOW (Defines the window attributes of your look)
/////////////////////////////////////////////////////////////////////
section window
list transalpha color.transparent  // We're calling a color that was defined previously in "section color"
list maptranscolor color.white  // On systems that don't support window transparency ( OS < Win2K) map that trans pixels to this color
int alphablend 255 // 255 == Full opacity

Titles

section title
   string fontname "Tahoma"
   int fontsize 7
   list fontcolor color.textcolor
   int texthint 4
   string fspec "$if(%tracknumber%,%tracknumber% - )[%artist% - ]$if(%title%,%title%,%_filename%) ->"
   bool scroll true
   int x 16
   int y 54
   int width 142
   int height 14

I still have some issues to work out with using the utf8api.dll so for now foo_looks is still unicode only (funny, it used to be ANSI only but everyone kept pressuring me to release a unicode version   )

RGBA transparency with layered windows, using UpdateLayeredWindow instead of SetLayeredWindowAttributes, are not terribly difficult. Now, the real fun comes if/when you want clicks on certain translucent parts, such as the shadows, to go through to the underlying windows. With layered windows, only clicks on fully transparent pixels go through. If you're not worried about that little element, then it should be no problem. Just a matter of calling UpdateLayeredWindow every time you change the bitmap. Or, if you're nuts, you could make each dynamic element of the window its own layered window... Hell, screw that.

what are all the available controls?

i mean like can i call history based previous and next functions or other things like call the album list etc?

maybe call visualizations etc?

also is there alpha transparency? (rather than color based?)

what are all the available controls?

Do you have any sample code using UpdateLayeredWindow, blendfuntions, etc.?

BYTE * ptr;
HBITMAP bitmap;
BITMAPINFOHEADER bmih;
bmih.biSize = sizeof(bmih);
bmih.biWidth = m_sSize.cx;
bmih.biHeight = m_sSize.cy;
bmih.biPlanes = 1;
bmih.biBitCount = 32;
bmih.biCompression = BI_RGB;
bmih.biSizeImage = 0;
bmih.biXPelsPerMeter = 0;
bmih.biYPelsPerMeter = 0;
bmih.biClrUsed = 0;
bmih.biClrImportant = 0;

bitmap = CreateDIBSection(0, (const BITMAPINFO *) &bmih, DIB_RGB_COLORS, (VOID **) &ptr, 0, 0);

POINT ptSrc = {0, 0};
BLENDFUNCTION blend = {AC_SRC_OVER, 0, alpha, AC_SRC_ALPHA};
HDC dDC = GetDC(NULL);
HDC hDC = CreateCompatibleDC(dDC);
HBITMAP pOldBmp = (HBITMAP) SelectObject(hDC, bitmap);
UpdateLayeredWindow(m_hWnd, dDC, &m_pPos, &m_sSize, hDC, &ptSrc, 0, &blend, ULW_ALPHA);
SelectObject(hDC, pOldBmp);
DeleteDC(hDC);
ReleaseDC(NULL, dDC);

Quote

i mean like can i call history based previous and next functions or other things like call the album list etc?

maybe call visualizations etc?

AFAIK not yet, but you could always ask danZ to implement them, in case you need them.  Wouldn't be the first feature request he implemented.

3. is that possible to toggle play/pause with a unique play/fake play button? what i want is the song to be paused when playing if i clicked on play and start playing from where it paused if clicked on it once again

Is it possible to implement the tabs of foobar in foo_looks?  If it is, how can it be done???