Thanks for the advice, but method darwRect() contains this.
[spoiler=Gui.drawRect()]
/**
* Draws a solid color rectangle with the specified coordinates and color. Args: x1, y1, x2, y2, color
*/
public static void drawRect(int par0, int par1, int par2, int par3, int par4)
{
int j1;
if (par0 < par2)
{
j1 = par0;
par0 = par2;
par2 = j1;
}
if (par1 < par3)
{
j1 = par1;
par1 = par3;
par3 = j1;
}
float f = (float)(par4 >> 24 & 255) / 255.0F;
float f1 = (float)(par4 >> 16 & 255) / 255.0F;
float f2 = (float)(par4 >> 8 & 255) / 255.0F;
float f3 = (float)(par4 & 255) / 255.0F;
Tessellator tessellator = Tessellator.instance;
GL11.glEnable(GL11.GL_BLEND);
GL11.glDisable(GL11.GL_TEXTURE_2D);
GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
GL11.glColor4f(f1, f2, f3, f);
tessellator.startDrawingQuads();
tessellator.addVertex((double)par0, (double)par3, 0.0D);
tessellator.addVertex((double)par2, (double)par3, 0.0D);
tessellator.addVertex((double)par2, (double)par1, 0.0D);
tessellator.addVertex((double)par0, (double)par1, 0.0D);
tessellator.draw();
GL11.glEnable(GL11.GL_TEXTURE_2D);
GL11.glDisable(GL11.GL_BLEND);
}