Revert "Emit widthChanged when resizing a resizable widget"

This reverts commit 436b81e56cb6ee8b8652a46c8a51130d3b5815d5.
Revert "Set correct bounds for the draggable area of a resizable widget"

This reverts commit ab9dd1ff34b2a5a5e3eef4434bdd3281b4f3d91a.
Revert "Fix the bug when resize starts when a User enters a mouse pointer into resizable widget at the first time"

This reverts commit 686c8413a4665a274e52dbdf4b1b51233d427980.
Revert "Create resizable widget"

This reverts commit 7720243d3b7ffc501afc758526fa700e552231b0.
Add a movable widget

A User can change position of the left corner of this widget by dragging
the mouse over it.
Add a resizable widget

A User can change the width of resizable widget by dragging the mouse over
movable area.