The features are only partially complete with the gadget-related parts.
It can run on Windows XP or later.
Try it and let me know if there are any problems, especially various drawing issues.
BTW, for testing purposes, the window background color is set randomly, it's not a bug.

https://www.dropbox.com/s/1c7w31d92j9er ... t.zip?dl=0
On Windows 7 English.

On Windows 10 Korean.

Currently implemented functionalities.
- Add all the PB native gadgets.
- Copy, Cut, Paste, Clone, Delete, Align. (hierarchical gadget structures, except for Clone, Align)
- Size, Move. (hierarchical gadget structures)
- DPI Awareness. (system, PB native)
How to use:
* Right click on the main canvas
Display an appropriate menu.
* Right mouse button (or Ctrl key) down + mouse wheel up/down on the main canvas
Change the window tab being displayed.
* Shift key down + mouse wheel up/down on the main canvas
Change the project tab being displayed.
* Drag and drop on the gadget object tree
Change the order of gadgets.
Change the order of tabs on the Panel gadget.
Swap two children of the Splitter gadget.
* Left click on a gadget
Select a gadget.
A gadget marked with the black handles:
- It is a base gadget for alignment.
- It will be added as the first child of the Splitter gadget.
* Ctrl + Left click on a gadget
Preserve previously selected gadgets, and select or deselect a gadget.
* Clone a gadget:
Depending on where the menu is called, the location of the new gadget being added changes.
(i.e. left 1/3, upper/lower part of middle 1/3, right 1/3 of a gadget)
* Press ESC key while moving/sizing/creating/selecting
Cancel the current operation.
There are two modes for operations. "Add/Manipulate" and "Move/Select" Modes.
In Add/Manipulate Mode: (crosshair cursor)
(to change the mode, click the middle mouse button or press the Space key on the main canvas)
* Left mouse button down + dragging
Draw a gadget.
Manipulate the V/H scroll bar of the ScrollArea gadget. (hand cursor)
Manipulate the separator of the Splitter gadget. (left-right arrows or up-down arrows cursor)
* Left click on a tab (or left-right button) of the Panel gadget
Change the active tab of the Panel gadget. (hand cursor)
In Move/Select Mode: (default arrow cursor)
* Left mouse button down + dragging
Select gadgets within a rectangular area.
* Shift key down + Left mouse button down and dragging
Preserve previously selected gadgets, and select gadgets within a rectangular area.
* Hold the left mouse button down for the default time(currently 200 ms). (arrow cursor in all directions)
Move a gadget on an unselected gadget.
Move the selected gadgets on a selected gadget.
* Shift key down + movement operation
Move + Change the parent of the selected/unselected gadgets.