Today's publication I a modern hotbar for all skids among you.
There are 2 modes - 1x wide & 1x compact.

In both modes, no strings have been added, instead this is conceivable.

Tutorial:

1. Opens the class "GuiIngame.java"
   (Eclipse: CTRL + SHIFT + R / IntelliJ: CTRL + N)

2. Navigates to the "func_180479_a" function
   (for those with better mappings it should be possible to consult the mappings (.xml file))

width Hotbar

Code:

ScaledResolution s = new ScaledResolution(Wrapper.mc, Wrapper.mc.displayWidth, Wrapper.mc.displayHeight);
RenderUtils.drawOldRect(0, s.getScaledHeight() - 23, s.getScaledWidth(), s.getScaledHeight(), new Color(0, 0, 0, 180).hashCode());

if (Wrapper.mc.thePlayer.inventory.currentItem == 0) {
    RenderUtils.drawOldRect((s.getScaledWidth() / 2) - 91 + Wrapper.mc.thePlayer.inventory.currentItem * 20, s.getScaledHeight() - 23, (s.getScaledWidth() / 2) + 91 - 20 * 8, s.getScaledHeight(), -1);
} else {
    RenderUtils.drawOldRect((s.getScaledWidth() / 2) - 91 + Wrapper.mc.thePlayer.inventory.currentItem * 20, s.getScaledHeight() - 23, (s.getScaledWidth() / 2) + 91 - 20 * (8 - Wrapper.mc.thePlayer.inventory.currentItem), s.getScaledHeight(), -1);
}

EntityPlayer var3 = (EntityPlayer) this.mc.func_175606_aa();
RenderHelper.enableGUIStandardItemLighting();

for (int var6 = 0; var6 < 9; ++var6) {
    int var7 = p_180479_1_.getScaledWidth() / 2 - 90 + var6 * 20 + 2;
    int var8 = p_180479_1_.getScaledHeight() - 16 - 3;
    this.func_175184_a(var6, var7, var8, p_180479_2_, var3);
}

RenderHelper.disableStandardItemLighting();
GlStateManager.disableRescaleNormal();
GlStateManager.disableBlend();

Smal Hotbar

ScaledResolution s = new ScaledResolution(Wrapper.mc, Wrapper.mc.displayWidth, Wrapper.mc.displayHeight);
RenderUtils.drawOldRect((s.getScaledWidth() / 2) - 91, s.getScaledHeight() - 23, (s.getScaledWidth() / 2) + 91, s.getScaledHeight(), new Color(0, 0, 0, 180).hashCode());

if (Wrapper.mc.thePlayer.inventory.currentItem == 0) {
    RenderUtils.drawOldRect((s.getScaledWidth() / 2) - 91 + Wrapper.mc.thePlayer.inventory.currentItem * 20, s.getScaledHeight() - 23, (s.getScaledWidth() / 2) + 91 - 20 * 8, s.getScaledHeight(), -1);
} else {
    RenderUtils.drawOldRect((s.getScaledWidth() / 2) - 91 + Wrapper.mc.thePlayer.inventory.currentItem * 20, s.getScaledHeight() - 23, (s.getScaledWidth() / 2) + 91 - 20 * (8 - Wrapper.mc.thePlayer.inventory.currentItem), s.getScaledHeight(), -1);
}

EntityPlayer var3 = (EntityPlayer) this.mc.func_175606_aa();
RenderHelper.enableGUIStandardItemLighting();

for (int var6 = 0; var6 < 9; ++var6) {
    int var7 = p_180479_1_.getScaledWidth() / 2 - 90 + var6 * 20 + 2;
    int var8 = p_180479_1_.getScaledHeight() - 16 - 3;
    this.func_175184_a(var6, var7, var8, p_180479_2_, var3);
}

RenderHelper.disableStandardItemLighting();
GlStateManager.disableRescaleNormal();
GlStateManager.disableBlend();

3.Replaces the code with the code from the respective spoiler
(save the original code; would recommend a SettingsManager to be able to switch between designs if necessary)

4. Starts the client and checks that everything is working properly.
   (Hot swap possible with existing session, but without guarantee)