[lerb]

Thank you Phanx I searched the forums before I posted and saw some similar responses, but I couldn't wrap my head around this anyhow. I don't know if it's because of oUF_Simple or my poor Lua knowledge, but probably a mix of the two

Anyhow, it's working! I'll post this here so people searching in the future might get something out of it. And, please, correct me if what I'm stating is wrong. It's based only on my poor Lua knowledge

oUF_Simple, like a lot of other layouts, has a core.lua that handles all the functions for the unitframes. These functions create castbars, healthbars and all that. Then we have the style.lua that "activates" all these for the different units aswell as some other options such as each units individual height and width, for example.

First, we need a function that handles the frame for Harmony using oUFs element ClassIcons.

This is what I added to my core.lua:

lib.gen_ClassIcons = function(f)
 
    local ci = CreateFrame("Frame", nil, f)
    ci:SetPoint('CENTER', f.Health, 'TOP', 0, 1)
    ci:SetSize(200, 16)
        for i = 1, 5 do
            ci[i] = CreateFrame("StatusBar", f:GetName().."_ClassBar"..i, f)
            ci[i]:SetSize(36, 16) 
            ci[i]:SetStatusBarTexture(cfg.statusbar_texture)
            ci[i]:SetFrameLevel(11)
            ci[i].SetVertexColor = ci[i].SetStatusBarColor
            CreateBorder(ci[i],12,1,1,1,2) -- !beautycase border
            local h = CreateFrame("Frame", nil, ci[i])
            h:SetFrameLevel(10)
            h:SetPoint("TOPLEFT",-4,3)
            h:SetPoint("BOTTOMRIGHT",4,-3)
            lib.gen_backdrop(h) 
            if (i == 1) then
                ci[i]:SetPoint('BOTTOMLEFT', f, 'TOPLEFT', -2, 7)
            else
                ci[i]:SetPoint('TOPLEFT', ci[i-1], "TOPRIGHT", 6, 0)
            end
            
        end
    f.ClassIcons = ci
  end

Here's what the player unit looked like in style.lua before adding ClassIcons:

--the player style
  local function CreatePlayerStyle(self)
    --style specific stuff
    self.width = 200
    self.height = 54
    self.mystyle = "player"
    init(self)
    self.Health:SetStatusBarColor(.35,.35,.35)
    self.Health.bg:SetVertexColor(.15,.15,.15)
    self.Power.colorClass = true
    self.Power.bg.multiplier = 0.2
    self.Power.Smooth = true
    self.Power.frequentUpdates = true
    lib.gen_castbar(self)
    lib.gen_portrait(self)
  end

Simply add "lib.gen_ClassIcons(self)" which will attach ClassIcons to this unitframe:

--the player style
  local function CreatePlayerStyle(self)
    --style specific stuff
    self.width = 200
    self.height = 54
    self.mystyle = "player"
    init(self)
    self.Health:SetStatusBarColor(.35,.35,.35)
    self.Health.bg:SetVertexColor(.15,.15,.15)
    self.Power.colorClass = true
    self.Power.bg.multiplier = 0.2
    self.Power.Smooth = true
    self.Power.frequentUpdates = true
    lib.gen_ClassIcons(self)
    lib.gen_castbar(self)
    lib.gen_portrait(self)
  end

I hope this makes sense and that it's somewhat well executed. I'm still learning, so any inputs are welcome Thank you again Phanx.