The Tab Order frame 3 enables you to define in which order the parts folders/categories are placed above the part library window. This way you can sort them from left to right, from most used to least used. This can be done by selecting a category in the list and using the "Move Up" and "Move Down" buttons. The list order from top to bottom represents left to right respectively above the parts library window. Pressing the "Alphabetical Order" button will sort the list in alphabetical order.
The Background Color frame 4 lets you change the background color of the library window in three situations: first is the default color, then the color that should be used when you have loaded a Budget file and only the budgeted parts are listed (see the Budget section for more details) and finally the color used when you have filtered the library with some keywords (see How to filter the Part Library for more details). In case of both budget and keyword filtering, it is the keyword filter color that will be used. You can set the same color for the three situations if you don't like to see color change.
The Budget frame 5 lets you specify a Budget file to load at startup (see the Budget section for more details). This is very convenient if you have created your own budget file with your actual LEGO® set collection. You can also decide if a part that doesn't have a budget set should be considered as having a budget of 0 (meaning, you don't have that part in your collection and therefore should not be authorized to used), or on the contrary having an infinite budget (meaning that you have that part in so huge quantity that you don't bother add a limitation to it).
Bubble Information frame 6 allows you to choose the information you will receive in the "tool tip" messages when you move the mouse over an icon in the parts library window. Note that in order to see the "tool tip" messages you must activate them by checking the "Display Bubble Info with:" checkbox or by right clicking on the part library window and selecting "Bubble Information".