Skew bounding box

If it is an path object, you can use Perspective effect. Draw an path object with four corners which looks like the wall you are going to stretch the things on. Select the "wall" path and the one you are about to stretch and from menu Effects (or was it the other one next to it) choose Transform → Perspective.

The extension mahfiaz refers to is:
menu 'Extensions > Modify Path > Perspective'

Maybe the description in the manual is also of use:
<http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Extensions-ModifyPath.html#Extensions-Perspective>

Tip: Make sure to draw the nodes of the quadrilateral path (defining the perspective outline) as described in the manual (first point: lower left, second point upper left, third point: upper right, fourth point lower right).
Another tip: the correct application of the extension depends on the selection order: object first, quadrilateral second. Always select the object to be transformed first, and then (with 'Shift+click') add the quadrilateral path to the selection, before applying the extension.

Thank you.