Implement suggestion from review and add missing input parameter description in docstring of the GUI constructor

Author: Jon Vegard Venås

src/setup_GUI.jl

@@ -42,6 +42,10 @@ to the old EnergyModelsX `case` dictionary.
   hovering objects to show information.
 - **`use_geomakie::Bool=true`** toggles the use of GeoMakie for plotting geographical
   designs when the `case` contains geographical information.
+- **`pre_plot_sub_components::Bool=true`** toggles whether or not to pre-plot all
+  sub-components of areas in the topology design. Setting this to `false` greatly
+  enhances performance for large cases, as the components of an `Area` are then
+  plotted on demand (on the `open` functionality).
 
 !!! warning "Reading model results from CSV-files"
     Reading model results from a directory (*i.e.*, `model::String` implying that the results

src/utils_GUI/topo_axis_utils.jl

@@ -714,10 +714,13 @@ function get_hover_string(obj::AbstractGUIObj)
     element = get_element(obj)
     label = get_element_label(element)
     inv_times = get_inv_times(obj)
-    inv_str = "$label ($(nameof(typeof(element))))"
+    io = IOBuffer()
+    print(io, "$label ($(nameof(typeof(element))))")
     if !isempty(inv_times)
         capex = get_capex(obj)
-        inv_str *= join(["\n\t$t: $(format_number(c))" for (t, c) ∈ zip(inv_times, capex)])
+        for (t, c) ∈ zip(inv_times, capex)
+            print(io, "\n\t", t, ": ", format_number(c))
+        end
     end
-    return inv_str
+    return String(take!(io))
 end