[1.11.2] Multi-line textbox cursor behaving funny

package silly511.aestheticeffect.gui;

import java.io.IOException;
import java.util.List;

import org.lwjgl.input.Keyboard;
import org.lwjgl.input.Mouse;

import com.google.common.collect.Lists;

import net.minecraft.client.gui.GuiButton;
import net.minecraft.client.gui.GuiScreen;
import net.minecraft.client.resources.I18n;
import net.minecraft.util.ChatAllowedCharacters;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.math.MathHelper;
import net.minecraft.world.World;
import silly511.aestheticeffect.tile.TileHologramProjector;

public class GuiHologramProjector extends GuiScreen {
	
	private List<String> text = Lists.newArrayList("");
	private int cursorX;
	private int cursorY;
	private int scroll;
	
	private BlockPos pos;
	private World world;
	private TileHologramProjector tile;
	
	public GuiHologramProjector(int x, int y, int z, World world) {
		this.pos = new BlockPos(x, y, z);
		this.world = world;
		this.tile = (TileHologramProjector) world.getTileEntity(pos);
	}

	@Override
	public void drawScreen(int mouseX, int mouseY, float partialTicks) {
		int x = 100;
		int y = 100;
		
		this.drawDefaultBackground();
		
		for (int i = 0; i < 15; i++) {
			if (i + scroll > text.size() - 1) break;
			
			this.mc.fontRendererObj.drawString(text.get(scroll + i), x, y + (mc.fontRendererObj.FONT_HEIGHT + 2) * i, 0xFFFFFF, false);
		}
		
		int lineWidth = this.mc.fontRendererObj.getStringWidth(text.get(cursorY).substring(0, cursorX)) + 1;
		this.mc.fontRendererObj.drawString("_", x + lineWidth, y + (mc.fontRendererObj.FONT_HEIGHT + 2) * (cursorY - scroll) + 2, 0xFFFFFF);
		
		super.drawScreen(mouseX, mouseY, partialTicks);
	}

	@Override
	protected void keyTyped(char typedChar, int keyCode) throws IOException {
		if (keyCode == Keyboard.KEY_ESCAPE) {
			this.mc.displayGuiScreen(null);
		} else if (keyCode == Keyboard.KEY_UP && this.cursorY > 0) {
			this.cursorY--;
			this.cursorX = MathHelper.clamp(this.cursorX, 0, this.text.get(cursorY).length());
		} else if (keyCode == Keyboard.KEY_DOWN && this.cursorY < this.text.size() - 1) {
			this.cursorY++;
			this.cursorX = MathHelper.clamp(this.cursorX, 0, this.text.get(cursorY).length());
		} else if (keyCode == Keyboard.KEY_LEFT && this.cursorX > 0) {
			this.cursorX--;
		} else if (keyCode == Keyboard.KEY_RIGHT && this.cursorX < this.text.get(cursorY).length()) {
			this.cursorX++;
		} else if (keyCode == Keyboard.KEY_RETURN) {
			String line = text.get(cursorY);
			
			text.set(cursorY, line.substring(0, cursorX));
			text.add(cursorY + 1, line.substring(cursorX, line.length()));
			
			cursorY++;
			cursorX = 0;
		} else if (keyCode == Keyboard.KEY_BACK && cursorX > 0) {
			cursorX--;
			
			text.set(cursorY, new StringBuilder(text.get(cursorY)).deleteCharAt(cursorX).toString());
		} else if (ChatAllowedCharacters.isAllowedCharacter(typedChar)) {
			String line = text.get(cursorY);
			
			if (line.length() + 1 > 255) return;
			
			text.set(cursorY, new StringBuilder(line).insert(cursorX, typedChar).toString());
			cursorX++;
		}
	}

	@Override
	public void handleMouseInput() throws IOException {
		int scrollDir = Mouse.getEventDWheel();
		
		if (scrollDir != 0) {
			if (this.scroll > 0 && scrollDir >= 1)
				this.scroll--;
			else if (this.scroll < text.size() - 1 && scrollDir <= -1)
				this.scroll++;
		}
		
		super.handleMouseInput();
	}

	@Override
	protected void actionPerformed(GuiButton button) throws IOException {
		if (button.id == 0) {
			this.mc.displayGuiScreen(null);
			//TODO
		}
	}

	@Override
	public void initGui() {
		Keyboard.enableRepeatEvents(true);
		
		this.addButton(new GuiButton(0, 0, 0, I18n.format("gui.done")));
	}

	@Override
	public void onGuiClosed() {
		Keyboard.enableRepeatEvents(false);
	}

	@Override
	public boolean doesGuiPauseGame() {
		return false;
	}

}