When I drag a widget to add it to the desktop a blue square appears to show the position where the widget will be positioned. This doesn't happen when I try to add a widget to the panel.
It's true that the other widgets move around to show the user that the widget will be placed in the empty space.

The problem is that most of the empty space of my panel is actually occupied by the task manager (icon only task manager), so when a widget is dragged over this empty space there is no feedback on whether the task manager widget has shrunken or not. Because of this often releasing the mouse button causes the widget to not be placed correctly.

Reproducible: Always

Steps to Reproduce:
1.Create an empty panel
2.Add icon only task manager to the panel
3.Try to add another plasmoid by dragging it to the empty space on the panel

Actual Results:  
Unless the plasmoid is positioned in the extreme right of the panel, the placement of the plasmoid will fail with no clear reason to the user

Expected Results:  
Showing a blue square where the plasmoid will be placed can be used as a feedback by the user to understand if he placed the plasmoid correctly before releasing the mouse button.