Fix initial "shivering" on desktop while dragging a building plan.

[apollovy]

• [ X] I have read the contribution guidelines.
• [ X] I have ensured that my code compiles, if applicable.
• [X ] I have ensured that any new features in this PR function correctly in-game, if applicable.

Hey. First of all, thank you for a great game.

Currently on desktop when the player puts a BuildPlan and then clicks that plan, the plan becomes moved and creates a "shivering" effect: you didn't mean to move it, but it moved. My PR addresses just this tiny annoyance. Thank you in advance :)