Reproduction steps:(Gif attached)
1) Open attached project.
2) Select sprite in the Asset window and hit Sprite Editor in Inspector.
3) Try to click on any Border values input field.

Expected result: Input field gets selected and accepts input via keyboard.

Actual result: In the upper left corner of Sprite Editor you are prompt to enter Sides value to "Change Shape" - this field blocks any other input fields and gets selected instead.

Note: You can still change Border values by dragging value names while holding down LMB.

Reproduced with: 5.3.1f1, 5.3.4.f1, 5.4.0b11
Does not reproduce with: 5.2.4f1(Read Edit)