I originally posted that because the scroll wheel wasn't working. That said, my entire Terraria client is broken now (vanilla included) so i can't get in-game to confirm this.I've been testing the mod in multiplayer (even though it's host and play) and only encountered this issue with the update I will be launching tomorrow (If I can fix this bug). For me, it was because it was loading null values at startup. But the value causing it did not exist in the published version. Can you still load the world in singleplayer?
The lag when resizing is kinda unavoidable, as it rebuilds the display list in any change to the size. But you can use the Scroll Wheel to scroll up or down on both the category and Item display panel. The scroll bar is just invisible because I wasn't able to make it change when clicked and dragged around.
Also, I'll be testing an update that will allow players in multiplayer to exchange research knowledge. Next update will be when that's fully tested.
Fixed my game and can confirm, scroll wheel does not work. If the amount of items on the page is more than the window can hold there is no way to see the bottom of the list.